item.cc 184 KB
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/* Copyright (C) 2000-2006 MySQL AB
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   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; version 2 of the License.
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   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
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   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


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#ifdef USE_PRAGMA_IMPLEMENTATION
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#pragma implementation				// gcc: Class implementation
#endif
#include "mysql_priv.h"
#include <m_ctype.h>
#include "my_dir.h"
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#include "sp_rcontext.h"
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#include "sp_head.h"
#include "sql_trigger.h"
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#include "sql_select.h"
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const String my_null_string("NULL", 4, default_charset_info);

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/****************************************************************************/

/* Hybrid_type_traits {_real} */

void Hybrid_type_traits::fix_length_and_dec(Item *item, Item *arg) const
{
  item->decimals= NOT_FIXED_DEC;
  item->max_length= item->float_length(arg->decimals);
}

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static const Hybrid_type_traits real_traits_instance;
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const Hybrid_type_traits *Hybrid_type_traits::instance()
{
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  return &real_traits_instance;
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}


my_decimal *
Hybrid_type_traits::val_decimal(Hybrid_type *val, my_decimal *to) const
{
  double2my_decimal(E_DEC_FATAL_ERROR, val->real, val->dec_buf);
  return val->dec_buf;
}


String *
Hybrid_type_traits::val_str(Hybrid_type *val, String *to, uint8 decimals) const
{
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  to->set_real(val->real, decimals, &my_charset_bin);
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  return to;
}

/* Hybrid_type_traits_decimal */
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static const Hybrid_type_traits_decimal decimal_traits_instance;
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const Hybrid_type_traits_decimal *Hybrid_type_traits_decimal::instance()
{
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  return &decimal_traits_instance;
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}


void
Hybrid_type_traits_decimal::fix_length_and_dec(Item *item, Item *arg) const
{
  item->decimals= arg->decimals;
  item->max_length= min(arg->max_length + DECIMAL_LONGLONG_DIGITS,
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                        DECIMAL_MAX_STR_LENGTH);
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}


void Hybrid_type_traits_decimal::set_zero(Hybrid_type *val) const
{
  my_decimal_set_zero(&val->dec_buf[0]);
  val->used_dec_buf_no= 0;
}


void Hybrid_type_traits_decimal::add(Hybrid_type *val, Field *f) const
{
  my_decimal_add(E_DEC_FATAL_ERROR,
                 &val->dec_buf[val->used_dec_buf_no ^ 1],
                 &val->dec_buf[val->used_dec_buf_no],
                 f->val_decimal(&val->dec_buf[2]));
  val->used_dec_buf_no^= 1;
}


void Hybrid_type_traits_decimal::div(Hybrid_type *val, ulonglong u) const
{
  int2my_decimal(E_DEC_FATAL_ERROR, u, TRUE, &val->dec_buf[2]);
  /* XXX: what is '4' for scale? */
  my_decimal_div(E_DEC_FATAL_ERROR,
                 &val->dec_buf[val->used_dec_buf_no ^ 1],
                 &val->dec_buf[val->used_dec_buf_no],
                 &val->dec_buf[2], 4);
  val->used_dec_buf_no^= 1;
}


longlong
Hybrid_type_traits_decimal::val_int(Hybrid_type *val, bool unsigned_flag) const
{
  longlong result;
  my_decimal2int(E_DEC_FATAL_ERROR, &val->dec_buf[val->used_dec_buf_no],
                 unsigned_flag, &result);
  return result;
}


double
Hybrid_type_traits_decimal::val_real(Hybrid_type *val) const
{
  my_decimal2double(E_DEC_FATAL_ERROR, &val->dec_buf[val->used_dec_buf_no],
                    &val->real);
  return val->real;
}


String *
Hybrid_type_traits_decimal::val_str(Hybrid_type *val, String *to,
                                    uint8 decimals) const
{
  my_decimal_round(E_DEC_FATAL_ERROR, &val->dec_buf[val->used_dec_buf_no],
                   decimals, FALSE, &val->dec_buf[2]);
  my_decimal2string(E_DEC_FATAL_ERROR, &val->dec_buf[2], 0, 0, 0, to);
  return to;
}

/* Hybrid_type_traits_integer */
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static const Hybrid_type_traits_integer integer_traits_instance;
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const Hybrid_type_traits_integer *Hybrid_type_traits_integer::instance()
{
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  return &integer_traits_instance;
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}

void
Hybrid_type_traits_integer::fix_length_and_dec(Item *item, Item *arg) const
{
  item->decimals= 0;
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  item->max_length= MY_INT64_NUM_DECIMAL_DIGITS;
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  item->unsigned_flag= 0;
}

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/*****************************************************************************
** Item functions
*****************************************************************************/

/* Init all special items */

void item_init(void)
{
  item_user_lock_init();
}

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/*
TODO: make this functions class dependent
*/
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bool Item::val_bool()
{
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  switch(result_type()) {
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  case INT_RESULT:
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    return val_int() != 0;
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  case DECIMAL_RESULT:
  {
    my_decimal decimal_value;
    my_decimal *val= val_decimal(&decimal_value);
    if (val)
      return !my_decimal_is_zero(val);
    return 0;
  }
  case REAL_RESULT:
  case STRING_RESULT:
    return val_real() != 0.0;
  case ROW_RESULT:
  default:
    DBUG_ASSERT(0);
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    return 0;                                   // Wrong (but safe)
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  }
}


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String *Item::val_string_from_real(String *str)
{
  double nr= val_real();
  if (null_value)
    return 0;					/* purecov: inspected */
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  str->set_real(nr,decimals, &my_charset_bin);
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  return str;
}


String *Item::val_string_from_int(String *str)
{
  longlong nr= val_int();
  if (null_value)
    return 0;
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  str->set_int(nr, unsigned_flag, &my_charset_bin);
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  return str;
}


String *Item::val_string_from_decimal(String *str)
{
  my_decimal dec_buf, *dec= val_decimal(&dec_buf);
  if (null_value)
    return 0;
  my_decimal_round(E_DEC_FATAL_ERROR, dec, decimals, FALSE, &dec_buf);
  my_decimal2string(E_DEC_FATAL_ERROR, &dec_buf, 0, 0, 0, str);
  return str;
}


my_decimal *Item::val_decimal_from_real(my_decimal *decimal_value)
{
  double nr= val_real();
  if (null_value)
    return 0;
  double2my_decimal(E_DEC_FATAL_ERROR, nr, decimal_value);
  return (decimal_value);
}


my_decimal *Item::val_decimal_from_int(my_decimal *decimal_value)
{
  longlong nr= val_int();
  if (null_value)
    return 0;
  int2my_decimal(E_DEC_FATAL_ERROR, nr, unsigned_flag, decimal_value);
  return decimal_value;
}


my_decimal *Item::val_decimal_from_string(my_decimal *decimal_value)
{
  String *res;
  char *end_ptr;
  if (!(res= val_str(&str_value)))
    return 0;                                   // NULL or EOM

  end_ptr= (char*) res->ptr()+ res->length();
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  if (str2my_decimal(E_DEC_FATAL_ERROR & ~E_DEC_BAD_NUM,
                     res->ptr(), res->length(), res->charset(),
                     decimal_value) & E_DEC_BAD_NUM)
  {
    push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                        ER_TRUNCATED_WRONG_VALUE,
                        ER(ER_TRUNCATED_WRONG_VALUE), "DECIMAL",
                        str_value.c_ptr());
  }
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  return decimal_value;
}


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my_decimal *Item::val_decimal_from_date(my_decimal *decimal_value)
{
  DBUG_ASSERT(fixed == 1);
  TIME ltime;
  if (get_date(&ltime, TIME_FUZZY_DATE))
  {
    my_decimal_set_zero(decimal_value);
    return 0;
  }
  return date2my_decimal(&ltime, decimal_value);
}


my_decimal *Item::val_decimal_from_time(my_decimal *decimal_value)
{
  DBUG_ASSERT(fixed == 1);
  TIME ltime;
  if (get_time(&ltime))
  {
    my_decimal_set_zero(decimal_value);
    return 0;
  }
  return date2my_decimal(&ltime, decimal_value);
}


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double Item::val_real_from_decimal()
{
  /* Note that fix_fields may not be called for Item_avg_field items */
  double result;
  my_decimal value_buff, *dec_val= val_decimal(&value_buff);
  if (null_value)
    return 0.0;
  my_decimal2double(E_DEC_FATAL_ERROR, dec_val, &result);
  return result;
}


longlong Item::val_int_from_decimal()
{
  /* Note that fix_fields may not be called for Item_avg_field items */
  longlong result;
  my_decimal value, *dec_val= val_decimal(&value);
  if (null_value)
    return 0;
  my_decimal2int(E_DEC_FATAL_ERROR, dec_val, unsigned_flag, &result);
  return result;
}

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int Item::save_time_in_field(Field *field)
{
  TIME ltime;
  if (get_time(&ltime))
    return set_field_to_null(field);
  field->set_notnull();
  return field->store_time(&ltime, MYSQL_TIMESTAMP_TIME);
}


int Item::save_date_in_field(Field *field)
{
  TIME ltime;
  if (get_date(&ltime, TIME_FUZZY_DATE))
    return set_field_to_null(field);
  field->set_notnull();
  return field->store_time(&ltime, MYSQL_TIMESTAMP_DATETIME);
}

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Item::Item():
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  rsize(0), name(0), orig_name(0), name_length(0), fixed(0),
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  is_autogenerated_name(TRUE),
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  collation(&my_charset_bin, DERIVATION_COERCIBLE)
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{
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  marker= 0;
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  maybe_null=null_value=with_sum_func=unsigned_flag=0;
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  decimals= 0; max_length= 0;
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  with_subselect= 0;
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  cmp_context= (Item_result)-1;
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  /* Put item in free list so that we can free all items at end */
  THD *thd= current_thd;
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  next= thd->free_list;
  thd->free_list= this;
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  /*
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    Item constructor can be called during execution other then SQL_COM
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    command => we should check thd->lex->current_select on zero (thd->lex
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    can be uninitialised)
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  */
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  if (thd->lex->current_select)
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  {
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    enum_parsing_place place= 
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      thd->lex->current_select->parsing_place;
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    if (place == SELECT_LIST ||
	place == IN_HAVING)
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      thd->lex->current_select->select_n_having_items++;
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  }
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}

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/*
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  Constructor used by Item_field, Item_*_ref & aggregate (sum) functions.
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  Used for duplicating lists in processing queries with temporary
  tables
*/
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Item::Item(THD *thd, Item *item):
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  rsize(0),
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  str_value(item->str_value),
  name(item->name),
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  orig_name(item->orig_name),
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  max_length(item->max_length),
  marker(item->marker),
  decimals(item->decimals),
  maybe_null(item->maybe_null),
  null_value(item->null_value),
  unsigned_flag(item->unsigned_flag),
  with_sum_func(item->with_sum_func),
  fixed(item->fixed),
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  collation(item->collation),
  cmp_context(item->cmp_context)
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{
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  next= thd->free_list;				// Put in free list
  thd->free_list= this;
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}

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uint Item::decimal_precision() const
{
  Item_result restype= result_type();

  if ((restype == DECIMAL_RESULT) || (restype == INT_RESULT))
    return min(my_decimal_length_to_precision(max_length, decimals, unsigned_flag),
               DECIMAL_MAX_PRECISION);
  return min(max_length, DECIMAL_MAX_PRECISION);
}


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void Item::print_item_w_name(String *str)
{
  print(str);
  if (name)
  {
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    THD *thd= current_thd;
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    str->append(STRING_WITH_LEN(" AS "));
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    append_identifier(thd, str, name, (uint) strlen(name));
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  }
}


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void Item::cleanup()
{
  DBUG_ENTER("Item::cleanup");
  fixed=0;
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  marker= 0;
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  if (orig_name)
    name= orig_name;
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  DBUG_VOID_RETURN;
}

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/*
  cleanup() item if it is 'fixed'

  SYNOPSIS
    cleanup_processor()
    arg - a dummy parameter, is not used here
*/

bool Item::cleanup_processor(byte *arg)
{
  if (fixed)
    cleanup();
  return FALSE;
}


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/*
  rename item (used for views, cleanup() return original name)

  SYNOPSIS
    Item::rename()
    new_name	new name of item;
*/

void Item::rename(char *new_name)
{
  /*
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    we can compare pointers to names here, because if name was not changed,
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    pointer will be same
  */
  if (!orig_name && new_name != name)
    orig_name= name;
  name= new_name;
}


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/*
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  Traverse item tree possibly transforming it (replacing items).
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  SYNOPSIS
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    Item::transform()
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      transformer    functor that performs transformation of a subtree
      arg            opaque argument passed to the functor

  DESCRIPTION
    This function is designed to ease transformation of Item trees.

    Re-execution note: every such transformation is registered for
    rollback by THD::change_item_tree() and is rolled back at the end
    of execution by THD::rollback_item_tree_changes().

    Therefore:

      - this function can not be used at prepared statement prepare
        (in particular, in fix_fields!), as only permanent
        transformation of Item trees are allowed at prepare.

      - the transformer function shall allocate new Items in execution
        memory root (thd->mem_root) and not anywhere else: allocated
        items will be gone in the end of execution.

    If you don't need to transform an item tree, but only traverse
    it, please use Item::walk() instead.


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  RETURN VALUE
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    Returns pointer to the new subtree root.  THD::change_item_tree()
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    should be called for it if transformation took place, i.e. if a
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    pointer to newly allocated item is returned.
*/

Item* Item::transform(Item_transformer transformer, byte *arg)
{
  DBUG_ASSERT(!current_thd->is_stmt_prepare());

  return (this->*transformer)(arg);
}


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Item_ident::Item_ident(Name_resolution_context *context_arg,
                       const char *db_name_arg,const char *table_name_arg,
		       const char *field_name_arg)
  :orig_db_name(db_name_arg), orig_table_name(table_name_arg),
   orig_field_name(field_name_arg), context(context_arg),
   db_name(db_name_arg), table_name(table_name_arg),
   field_name(field_name_arg),
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   alias_name_used(FALSE), cached_field_index(NO_CACHED_FIELD_INDEX),
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   cached_table(0), depended_from(0)
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{
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  name = (char*) field_name_arg;
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}

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/* Constructor used by Item_field & Item_*_ref (see Item comment) */
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Item_ident::Item_ident(THD *thd, Item_ident *item)
  :Item(thd, item),
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   orig_db_name(item->orig_db_name),
   orig_table_name(item->orig_table_name), 
   orig_field_name(item->orig_field_name),
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   context(item->context),
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   db_name(item->db_name),
   table_name(item->table_name),
   field_name(item->field_name),
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   alias_name_used(item->alias_name_used),
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   cached_field_index(item->cached_field_index),
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   cached_table(item->cached_table),
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   depended_from(item->depended_from)
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{}
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void Item_ident::cleanup()
{
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  DBUG_ENTER("Item_ident::cleanup");
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#ifdef CANT_BE_USED_AS_MEMORY_IS_FREED
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		       db_name ? db_name : "(null)",
                       orig_db_name ? orig_db_name : "(null)",
		       table_name ? table_name : "(null)",
                       orig_table_name ? orig_table_name : "(null)",
		       field_name ? field_name : "(null)",
                       orig_field_name ? orig_field_name : "(null)"));
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#endif
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  Item::cleanup();
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  db_name= orig_db_name; 
  table_name= orig_table_name;
  field_name= orig_field_name;
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  depended_from= 0;
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  DBUG_VOID_RETURN;
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}

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bool Item_ident::remove_dependence_processor(byte * arg)
{
  DBUG_ENTER("Item_ident::remove_dependence_processor");
  if (depended_from == (st_select_lex *) arg)
    depended_from= 0;
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  DBUG_RETURN(0);
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}


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/*
  Store the pointer to this item field into a list if not already there.

  SYNOPSIS
    Item_field::collect_item_field_processor()
    arg  pointer to a List<Item_field>

  DESCRIPTION
    The method is used by Item::walk to collect all unique Item_field objects
    from a tree of Items into a set of items represented as a list.

  IMPLEMENTATION
    Item_cond::walk() and Item_func::walk() stop the evaluation of the
    processor function for its arguments once the processor returns
    true.Therefore in order to force this method being called for all item
    arguments in a condition the method must return false.

  RETURN
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    FALSE to force the evaluation of collect_item_field_processor
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          for the subsequent items.
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*/

bool Item_field::collect_item_field_processor(byte *arg)
{
  DBUG_ENTER("Item_field::collect_item_field_processor");
  DBUG_PRINT("info", ("%s", field->field_name ? field->field_name : "noname"));
  List<Item_field> *item_list= (List<Item_field>*) arg;
  List_iterator<Item_field> item_list_it(*item_list);
  Item_field *curr_item;
  while ((curr_item= item_list_it++))
  {
    if (curr_item->eq(this, 1))
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      DBUG_RETURN(FALSE); /* Already in the set. */
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  }
  item_list->push_back(this);
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  DBUG_RETURN(FALSE);
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}


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/*
  Check if an Item_field references some field from a list of fields.

  SYNOPSIS
    Item_field::find_item_in_field_list_processor
    arg   Field being compared, arg must be of type Field

  DESCRIPTION
    Check whether the Item_field represented by 'this' references any
    of the fields in the keyparts passed via 'arg'. Used with the
    method Item::walk() to test whether any keypart in a sequence of
    keyparts is referenced in an expression.

  RETURN
    TRUE  if 'this' references the field 'arg'
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    FALSE otherwise
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*/
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bool Item_field::find_item_in_field_list_processor(byte *arg)
{
  KEY_PART_INFO *first_non_group_part= *((KEY_PART_INFO **) arg);
  KEY_PART_INFO *last_part= *(((KEY_PART_INFO **) arg) + 1);
  KEY_PART_INFO *cur_part;

  for (cur_part= first_non_group_part; cur_part != last_part; cur_part++)
  {
    if (field->eq(cur_part->field))
      return TRUE;
  }
  return FALSE;
}


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/*
  Mark field in read_map

  NOTES
    This is used by filesort to register used fields in a a temporary
    column read set or to register used fields in a view
*/

bool Item_field::register_field_in_read_map(byte *arg)
{
  TABLE *table= (TABLE *) arg;
  if (field->table == table || !table)
    bitmap_set_bit(field->table->read_set, field->field_index);
  return 0;
}


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bool Item::check_cols(uint c)
{
  if (c != 1)
  {
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    my_error(ER_OPERAND_COLUMNS, MYF(0), c);
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    return 1;
  }
  return 0;
}

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void Item::set_name(const char *str, uint length, CHARSET_INFO *cs)
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{
  if (!length)
  {
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    /* Empty string, used by AS or internal function like last_insert_id() */
    name= (char*) str;
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    name_length= 0;
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    return;
  }
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  if (cs->ctype)
  {
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    uint orig_len= length;
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    /*
      This will probably need a better implementation in the future:
      a function in CHARSET_INFO structure.
    */
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    while (length && !my_isgraph(cs,*str))
    {						// Fix problem with yacc
      length--;
      str++;
    }
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    if (orig_len != length && !is_autogenerated_name)
      push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                          ER_REMOVED_SPACES, ER(ER_REMOVED_SPACES),
                          str + length - orig_len);

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  }
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  if (!my_charset_same(cs, system_charset_info))
  {
    uint32 res_length;
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    name= sql_strmake_with_convert(str, name_length= length, cs,
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				   MAX_ALIAS_NAME, system_charset_info,
				   &res_length);
  }
  else
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    name= sql_strmake(str, (name_length= min(length,MAX_ALIAS_NAME)));
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}

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/*
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  This function is called when:
  - Comparing items in the WHERE clause (when doing where optimization)
  - When trying to find an ORDER BY/GROUP BY item in the SELECT part
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*/

bool Item::eq(const Item *item, bool binary_cmp) const
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{
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  /*
    Note, that this is never TRUE if item is a Item_param:
    for all basic constants we have special checks, and Item_param's
    type() can be only among basic constant types.
  */
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  return type() == item->type() && name && item->name &&
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    !my_strcasecmp(system_charset_info,name,item->name);
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}

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Item *Item::safe_charset_converter(CHARSET_INFO *tocs)
{
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  Item_func_conv_charset *conv= new Item_func_conv_charset(this, tocs, 1);
  return conv->safe ? conv : NULL;
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}


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/*
  Created mostly for mysql_prepare_table(). Important
  when a string ENUM/SET column is described with a numeric default value:

  CREATE TABLE t1(a SET('a') DEFAULT 1);

  We cannot use generic Item::safe_charset_converter(), because
  the latter returns a non-fixed Item, so val_str() crashes afterwards.
  Override Item_num method, to return a fixed item.
*/
Item *Item_num::safe_charset_converter(CHARSET_INFO *tocs)
{
  Item_string *conv;
  char buf[64];
  String *s, tmp(buf, sizeof(buf), &my_charset_bin);
  s= val_str(&tmp);
  if ((conv= new Item_string(s->ptr(), s->length(), s->charset())))
  {
    conv->str_value.copy();
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    conv->str_value.mark_as_const();
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  }
  return conv;
}


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Item *Item_static_float_func::safe_charset_converter(CHARSET_INFO *tocs)
{
  Item_string *conv;
  char buf[64];
  String *s, tmp(buf, sizeof(buf), &my_charset_bin);
  s= val_str(&tmp);
  if ((conv= new Item_static_string_func(func_name, s->ptr(), s->length(),
                                         s->charset())))
  {
    conv->str_value.copy();
    conv->str_value.mark_as_const();
  }
  return conv;
}


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Item *Item_string::safe_charset_converter(CHARSET_INFO *tocs)
{
  Item_string *conv;
  uint conv_errors;
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  char *ptr;
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  String tmp, cstr, *ostr= val_str(&tmp);
  cstr.copy(ostr->ptr(), ostr->length(), ostr->charset(), tocs, &conv_errors);
  if (conv_errors || !(conv= new Item_string(cstr.ptr(), cstr.length(),
                                             cstr.charset(),
                                             collation.derivation)))
  {
    /*
      Safe conversion is not possible (or EOM).
      We could not convert a string into the requested character set
      without data loss. The target charset does not cover all the
      characters from the string. Operation cannot be done correctly.
    */
    return NULL;
  }
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  if (!(ptr= current_thd->memdup(cstr.ptr(), cstr.length() + 1 )))
    return NULL;
  conv->str_value.set(ptr, cstr.length(), cstr.charset());
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  /* Ensure that no one is going to change the result string */
  conv->str_value.mark_as_const();
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  return conv;
}


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Item *Item_param::safe_charset_converter(CHARSET_INFO *tocs)
{
  if (const_item())
  {
    uint cnv_errors;
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    String *ostr= val_str(&cnvstr);
    cnvitem->str_value.copy(ostr->ptr(), ostr->length(),
                            ostr->charset(), tocs, &cnv_errors);
    if (cnv_errors)
       return NULL;
    cnvitem->str_value.mark_as_const();
    cnvitem->max_length= cnvitem->str_value.numchars() * tocs->mbmaxlen;
    return cnvitem;
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  }
  return NULL;
}


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Item *Item_static_string_func::safe_charset_converter(CHARSET_INFO *tocs)
{
  Item_string *conv;
  uint conv_errors;
  String tmp, cstr, *ostr= val_str(&tmp);
  cstr.copy(ostr->ptr(), ostr->length(), ostr->charset(), tocs, &conv_errors);
  if (conv_errors ||
      !(conv= new Item_static_string_func(func_name,
                                          cstr.ptr(), cstr.length(),
                                          cstr.charset(),
                                          collation.derivation)))
  {
    /*
      Safe conversion is not possible (or EOM).
      We could not convert a string into the requested character set
      without data loss. The target charset does not cover all the
      characters from the string. Operation cannot be done correctly.
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    */
    return NULL;
  }
  conv->str_value.copy();
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  /* Ensure that no one is going to change the result string */
  conv->str_value.mark_as_const();
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  return conv;
}


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bool Item_string::eq(const Item *item, bool binary_cmp) const
{
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  if (type() == item->type() && item->basic_const_item())
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  {
    if (binary_cmp)
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      return !stringcmp(&str_value, &item->str_value);
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    return (collation.collation == item->collation.collation &&
	    !sortcmp(&str_value, &item->str_value, collation.collation));
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  }
  return 0;
}


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/*
  Get the value of the function as a TIME structure.
  As a extra convenience the time structure is reset on error!
 */

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bool Item::get_date(TIME *ltime,uint fuzzydate)
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{
  char buff[40];
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  String tmp(buff,sizeof(buff), &my_charset_bin),*res;
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  if (!(res=val_str(&tmp)) ||
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      str_to_datetime_with_warn(res->ptr(), res->length(),
                                ltime, fuzzydate) <= MYSQL_TIMESTAMP_ERROR)
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  {
    bzero((char*) ltime,sizeof(*ltime));
    return 1;
  }
  return 0;
}

/*
  Get time of first argument.
  As a extra convenience the time structure is reset on error!
 */

bool Item::get_time(TIME *ltime)
{
  char buff[40];
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  String tmp(buff,sizeof(buff),&my_charset_bin),*res;
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  if (!(res=val_str(&tmp)) ||
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      str_to_time_with_warn(res->ptr(), res->length(), ltime))
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  {
    bzero((char*) ltime,sizeof(*ltime));
    return 1;
  }
  return 0;
}

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CHARSET_INFO *Item::default_charset()
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{
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  return current_thd->variables.collation_connection;
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}

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/*
  Save value in field, but don't give any warnings

  NOTES
   This is used to temporary store and retrieve a value in a column,
   for example in opt_range to adjust the key value to fit the column.
*/

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int Item::save_in_field_no_warnings(Field *field, bool no_conversions)
{
  int res;
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  TABLE *table= field->table;
  THD *thd= table->in_use;
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  enum_check_fields tmp= thd->count_cuted_fields;
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  my_bitmap_map *old_map= dbug_tmp_use_all_columns(table, table->write_set);
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  thd->count_cuted_fields= CHECK_FIELD_IGNORE;
  res= save_in_field(field, no_conversions);
  thd->count_cuted_fields= tmp;
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  dbug_tmp_restore_column_map(table->write_set, old_map);
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  return res;
}


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/*****************************************************************************
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  Item_sp_variable methods
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*****************************************************************************/
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Item_sp_variable::Item_sp_variable(char *sp_var_name_str,
                                   uint sp_var_name_length)
  :m_thd(0)
#ifndef DBUG_OFF
   , m_sp(0)
#endif
{
  m_name.str= sp_var_name_str;
  m_name.length= sp_var_name_length;
}


bool Item_sp_variable::fix_fields(THD *thd, Item **)
{
  Item *it;

  m_thd= thd; /* NOTE: this must be set before any this_xxx() */
  it= this_item();

  DBUG_ASSERT(it->fixed);

  max_length= it->max_length;
  decimals= it->decimals;
  unsigned_flag= it->unsigned_flag;
  fixed= 1;
  collation.set(it->collation.collation, it->collation.derivation);

  return FALSE;
}


double Item_sp_variable::val_real()
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{
  DBUG_ASSERT(fixed);
  Item *it= this_item();
  double ret= it->val_real();
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  null_value= it->null_value;
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  return ret;
}


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longlong Item_sp_variable::val_int()
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{
  DBUG_ASSERT(fixed);
  Item *it= this_item();
  longlong ret= it->val_int();
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  null_value= it->null_value;
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  return ret;
}


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String *Item_sp_variable::val_str(String *sp)
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{
  DBUG_ASSERT(fixed);
  Item *it= this_item();
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  String *res= it->val_str(sp);
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  null_value= it->null_value;
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  if (!res)
    return NULL;

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  /*
    This way we mark returned value of val_str as const,
    so that various functions (e.g. CONCAT) won't try to
    modify the value of the Item. Analogous mechanism is
    implemented for Item_param.
    Without this trick Item_splocal could be changed as a
    side-effect of expression computation. Here is an example
    of what happens without it: suppose x is varchar local
    variable in a SP with initial value 'ab' Then
      select concat(x,'c');
    would change x's value to 'abc', as Item_func_concat::val_str()
    would use x's internal buffer to compute the result.
    This is intended behaviour of Item_func_concat. Comments to
    Item_param class contain some more details on the topic.
  */
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  if (res != &str_value)
    str_value.set(res->ptr(), res->length(), res->charset());
  else
    res->mark_as_const();
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  return &str_value;
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}


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my_decimal *Item_sp_variable::val_decimal(my_decimal *decimal_value)
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{
  DBUG_ASSERT(fixed);
  Item *it= this_item();
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  my_decimal *val= it->val_decimal(decimal_value);
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  null_value= it->null_value;
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  return val;
}


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bool Item_sp_variable::is_null()
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{
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  return this_item()->is_null();
}


/*****************************************************************************
  Item_splocal methods
*****************************************************************************/

Item_splocal::Item_splocal(const LEX_STRING &sp_var_name,
                           uint sp_var_idx,
                           enum_field_types sp_var_type,
                           uint pos_in_q)
  :Item_sp_variable(sp_var_name.str, sp_var_name.length),
   m_var_idx(sp_var_idx), pos_in_query(pos_in_q)
{
  maybe_null= TRUE;

  m_type= sp_map_item_type(sp_var_type);
  m_result_type= sp_map_result_type(sp_var_type);
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}


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Item *
Item_splocal::this_item()
{
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  DBUG_ASSERT(m_sp == m_thd->spcont->sp);

  return m_thd->spcont->get_item(m_var_idx);
}

const Item *
Item_splocal::this_item() const
{
  DBUG_ASSERT(m_sp == m_thd->spcont->sp);

  return m_thd->spcont->get_item(m_var_idx);
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}

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Item **
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Item_splocal::this_item_addr(THD *thd, Item **)
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{
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  DBUG_ASSERT(m_sp == thd->spcont->sp);

  return thd->spcont->get_item_addr(m_var_idx);
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}

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void Item_splocal::print(String *str)
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{
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  str->reserve(m_name.length+8);
  str->append(m_name.str, m_name.length);
  str->append('@');
  str->qs_append(m_var_idx);
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}

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bool Item_splocal::set_value(THD *thd, sp_rcontext *ctx, Item **it)
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{
  return ctx->set_variable(thd, get_var_idx(), it);
}


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/*****************************************************************************
  Item_case_expr methods
*****************************************************************************/

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Item_case_expr::Item_case_expr(uint case_expr_id)
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  :Item_sp_variable( C_STRING_WITH_LEN("case_expr")),
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   m_case_expr_id(case_expr_id)
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{
}


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Item *
Item_case_expr::this_item()
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{
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  DBUG_ASSERT(m_sp == m_thd->spcont->sp);

  return m_thd->spcont->get_case_expr(m_case_expr_id);
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}


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const Item *
Item_case_expr::this_item() const
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{
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  DBUG_ASSERT(m_sp == m_thd->spcont->sp);

  return m_thd->spcont->get_case_expr(m_case_expr_id);
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}


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Item **
Item_case_expr::this_item_addr(THD *thd, Item **)
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{
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  DBUG_ASSERT(m_sp == thd->spcont->sp);

  return thd->spcont->get_case_expr_addr(m_case_expr_id);
}


void Item_case_expr::print(String *str)
{
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  if (str->reserve(MAX_INT_WIDTH + sizeof("case_expr@")))
    return;                                    /* purecov: inspected */
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  VOID(str->append(STRING_WITH_LEN("case_expr@")));
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  str->qs_append(m_case_expr_id);
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}


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/*****************************************************************************
  Item_name_const methods
*****************************************************************************/
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double Item_name_const::val_real()
{
  DBUG_ASSERT(fixed);
  double ret= value_item->val_real();
  null_value= value_item->null_value;
  return ret;
}


longlong Item_name_const::val_int()
{
  DBUG_ASSERT(fixed);
  longlong ret= value_item->val_int();
  null_value= value_item->null_value;
  return ret;
}


String *Item_name_const::val_str(String *sp)
{
  DBUG_ASSERT(fixed);
  String *ret= value_item->val_str(sp);
  null_value= value_item->null_value;
  return ret;
}


my_decimal *Item_name_const::val_decimal(my_decimal *decimal_value)
{
  DBUG_ASSERT(fixed);
  my_decimal *val= value_item->val_decimal(decimal_value);
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  null_value= value_item->null_value;
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  return val;
}


bool Item_name_const::is_null()
{
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  return value_item->is_null();
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}

Item::Type Item_name_const::type() const
{
  return value_item->type();
}


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bool Item_name_const::fix_fields(THD *thd, Item **ref)
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{
  char buf[128];
  String *item_name;
  String s(buf, sizeof(buf), &my_charset_bin);
  s.length(0);

  if (value_item->fix_fields(thd, &value_item) ||
      name_item->fix_fields(thd, &name_item))
    return TRUE;
  if (!(value_item->const_item() && name_item->const_item()))
    return TRUE;

  if (!(item_name= name_item->val_str(&s)))
    return TRUE; /* Can't have a NULL name */

  set_name(item_name->ptr(), (uint) item_name->length(), system_charset_info);
  max_length= value_item->max_length;
  decimals= value_item->decimals;
  fixed= 1;
  return FALSE;
}


void Item_name_const::print(String *str)
{
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  str->append(STRING_WITH_LEN("NAME_CONST("));
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  name_item->print(str);
  str->append(',');
  value_item->print(str);
  str->append(')');
}

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/*
 need a special class to adjust printing : references to aggregate functions 
 must not be printed as refs because the aggregate functions that are added to
 the front of select list are not printed as well.
*/
class Item_aggregate_ref : public Item_ref
{
public:
  Item_aggregate_ref(Name_resolution_context *context_arg, Item **item,
                  const char *table_name_arg, const char *field_name_arg)
    :Item_ref(context_arg, item, table_name_arg, field_name_arg) {}

  void print (String *str)
  {
    if (ref)
      (*ref)->print(str);
    else
      Item_ident::print(str);
  }
};


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/*
  Move SUM items out from item tree and replace with reference

  SYNOPSIS
    split_sum_func2()
    thd			Thread handler
    ref_pointer_array	Pointer to array of reference fields
    fields		All fields in select
    ref			Pointer to item
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    skip_registered     <=> function be must skipped for registered SUM items
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  NOTES
   This is from split_sum_func2() for items that should be split

   All found SUM items are added FIRST in the fields list and
   we replace the item with a reference.

   thd->fatal_error() may be called if we are out of memory
*/


void Item::split_sum_func2(THD *thd, Item **ref_pointer_array,
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                           List<Item> &fields, Item **ref, 
                           bool skip_registered)
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{
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  /* An item of type Item_sum  is registered <=> ref_by != 0 */ 
  if (type() == SUM_FUNC_ITEM && skip_registered && 
      ((Item_sum *) this)->ref_by)
    return;                                                 
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  if ((type() != SUM_FUNC_ITEM && with_sum_func) ||
      (type() == FUNC_ITEM &&
       (((Item_func *) this)->functype() == Item_func::ISNOTNULLTEST_FUNC ||
        ((Item_func *) this)->functype() == Item_func::TRIG_COND_FUNC)))
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  {
    /* Will split complicated items and ignore simple ones */
    split_sum_func(thd, ref_pointer_array, fields);
  }
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  else if ((type() == SUM_FUNC_ITEM || (used_tables() & ~PARAM_TABLE_BIT)) &&
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           type() != SUBSELECT_ITEM &&
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           (type() != REF_ITEM ||
           ((Item_ref*)this)->ref_type() == Item_ref::VIEW_REF))
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  {
    /*
      Replace item with a reference so that we can easily calculate
      it (in case of sum functions) or copy it (in case of fields)

      The test above is to ensure we don't do a reference for things
      that are constants (PARAM_TABLE_BIT is in effect a constant)
      or already referenced (for example an item in HAVING)
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      Exception is Item_direct_view_ref which we need to convert to
      Item_ref to allow fields from view being stored in tmp table.
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    */
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    Item_aggregate_ref *item_ref;
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    uint el= fields.elements;
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    Item *real_itm= real_item();
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    ref_pointer_array[el]= real_itm;
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    if (!(item_ref= new Item_aggregate_ref(&thd->lex->current_select->context,
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                                           ref_pointer_array + el, 0, name)))
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      return;                                   // fatal_error is set
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    if (type() == SUM_FUNC_ITEM)
      item_ref->depended_from= ((Item_sum *) this)->depended_from(); 
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    fields.push_front(real_itm);
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    thd->change_item_tree(ref, item_ref);
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  }
}


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/*
   Aggregate two collations together taking
   into account their coercibility (aka derivation):

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   0 == DERIVATION_EXPLICIT  - an explicitly written COLLATE clause
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   1 == DERIVATION_NONE      - a mix of two different collations
   2 == DERIVATION_IMPLICIT  - a column
   3 == DERIVATION_COERCIBLE - a string constant

   The most important rules are:

   1. If collations are the same:
      chose this collation, and the strongest derivation.

   2. If collations are different:
     - Character sets may differ, but only if conversion without
       data loss is possible. The caller provides flags whether
       character set conversion attempts should be done. If no
       flags are substituted, then the character sets must be the same.
       Currently processed flags are:
         MY_COLL_ALLOW_SUPERSET_CONV  - allow conversion to a superset
         MY_COLL_ALLOW_COERCIBLE_CONV - allow conversion of a coercible value
     - two EXPLICIT collations produce an error, e.g. this is wrong:
       CONCAT(expr1 collate latin1_swedish_ci, expr2 collate latin1_german_ci)
     - the side with smaller derivation value wins,
       i.e. a column is stronger than a string constant,
       an explicit COLLATE clause is stronger than a column.
     - if derivations are the same, we have DERIVATION_NONE,
       we'll wait for an explicit COLLATE clause which possibly can
       come from another argument later: for example, this is valid,
       but we don't know yet when collecting the first two arguments:
         CONCAT(latin1_swedish_ci_column,
                latin1_german1_ci_column,
                expr COLLATE latin1_german2_ci)
*/
bool DTCollation::aggregate(DTCollation &dt, uint flags)
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{
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  if (!my_charset_same(collation, dt.collation))
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  {
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    /* 
       We do allow to use binary strings (like BLOBS)
       together with character strings.
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       Binaries have more precedence than a character
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       string of the same derivation.
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    */
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    if (collation == &my_charset_bin)
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    {
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      if (derivation <= dt.derivation)
	; // Do nothing
      else
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      {
	set(dt); 
      }
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    }
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    else if (dt.collation == &my_charset_bin)
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    {
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      if (dt.derivation <= derivation)
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      {
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        set(dt);
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      }
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      else
       ; // Do nothing
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    }
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    else if ((flags & MY_COLL_ALLOW_SUPERSET_CONV) &&
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             collation->state & MY_CS_UNICODE &&
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             (derivation < dt.derivation ||
             (derivation == dt.derivation &&
             !(dt.collation->state & MY_CS_UNICODE))))
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    {
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      // Do nothing
    }
    else if ((flags & MY_COLL_ALLOW_SUPERSET_CONV) &&
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             dt.collation->state & MY_CS_UNICODE &&
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             (dt.derivation < derivation ||
              (dt.derivation == derivation &&
             !(collation->state & MY_CS_UNICODE))))
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    {
      set(dt);
    }
    else if ((flags & MY_COLL_ALLOW_COERCIBLE_CONV) &&
             derivation < dt.derivation &&
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             dt.derivation >= DERIVATION_SYSCONST)
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    {
      // Do nothing;
    }
    else if ((flags & MY_COLL_ALLOW_COERCIBLE_CONV) &&
             dt.derivation < derivation &&
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             derivation >= DERIVATION_SYSCONST)
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    {
      set(dt);
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    }
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    else
    {
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      // Cannot apply conversion
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      set(0, DERIVATION_NONE);
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      return 1;
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    }
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  }
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  else if (derivation < dt.derivation)
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  {
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    // Do nothing
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  }
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  else if (dt.derivation < derivation)
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  {
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    set(dt);
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  }
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  else
  { 
    if (collation == dt.collation)
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    {
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      // Do nothing
    }
    else 
    {
      if (derivation == DERIVATION_EXPLICIT)
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      {
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	set(0, DERIVATION_NONE);
	return 1;
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      }
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      if (collation->state & MY_CS_BINSORT)
        return 0;
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      if (dt.collation->state & MY_CS_BINSORT)
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      {
        set(dt);
        return 0;
      }
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      CHARSET_INFO *bin= get_charset_by_csname(collation->csname, 
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                                               MY_CS_BINSORT,MYF(0));
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      set(bin, DERIVATION_NONE);
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    }
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  }
  return 0;
}

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/******************************/
static
void my_coll_agg_error(DTCollation &c1, DTCollation &c2, const char *fname)
{
  my_error(ER_CANT_AGGREGATE_2COLLATIONS,MYF(0),
           c1.collation->name,c1.derivation_name(),
           c2.collation->name,c2.derivation_name(),
           fname);
}


static
void my_coll_agg_error(DTCollation &c1, DTCollation &c2, DTCollation &c3,
                       const char *fname)
{
  my_error(ER_CANT_AGGREGATE_3COLLATIONS,MYF(0),
  	   c1.collation->name,c1.derivation_name(),
	   c2.collation->name,c2.derivation_name(),
	   c3.collation->name,c3.derivation_name(),
	   fname);
}


static
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void my_coll_agg_error(Item** args, uint count, const char *fname,
                       int item_sep)
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{
  if (count == 2)
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    my_coll_agg_error(args[0]->collation, args[item_sep]->collation, fname);
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  else if (count == 3)
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    my_coll_agg_error(args[0]->collation, args[item_sep]->collation,
                      args[2*item_sep]->collation, fname);
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  else
    my_error(ER_CANT_AGGREGATE_NCOLLATIONS,MYF(0),fname);
}


bool agg_item_collations(DTCollation &c, const char *fname,
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                         Item **av, uint count, uint flags, int item_sep)
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{
  uint i;
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  Item **arg;
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  c.set(av[0]->collation);
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  for (i= 1, arg= &av[item_sep]; i < count; i++, arg++)
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  {
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    if (c.aggregate((*arg)->collation, flags))
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    {
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      my_coll_agg_error(av, count, fname, item_sep);
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      return TRUE;
    }
  }
  if ((flags & MY_COLL_DISALLOW_NONE) &&
      c.derivation == DERIVATION_NONE)
  {
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    my_coll_agg_error(av, count, fname, item_sep);
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    return TRUE;
  }
  return FALSE;
}


bool agg_item_collations_for_comparison(DTCollation &c, const char *fname,
                                        Item **av, uint count, uint flags)
{
  return (agg_item_collations(c, fname, av, count,
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                              flags | MY_COLL_DISALLOW_NONE, 1));
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}


/* 
  Collect arguments' character sets together.
  We allow to apply automatic character set conversion in some cases.
  The conditions when conversion is possible are:
  - arguments A and B have different charsets
  - A wins according to coercibility rules
    (i.e. a column is stronger than a string constant,
     an explicit COLLATE clause is stronger than a column)
  - character set of A is either superset for character set of B,
    or B is a string constant which can be converted into the
    character set of A without data loss.
    
  If all of the above is true, then it's possible to convert
  B into the character set of A, and then compare according
  to the collation of A.
  
  For functions with more than two arguments:

    collect(A,B,C) ::= collect(collect(A,B),C)
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  Since this function calls THD::change_item_tree() on the passed Item **
  pointers, it is necessary to pass the original Item **'s, not copies.
  Otherwise their values will not be properly restored (see BUG#20769).
  If the items are not consecutive (eg. args[2] and args[5]), use the
  item_sep argument, ie.

    agg_item_charsets(coll, fname, &args[2], 2, flags, 3)

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*/

bool agg_item_charsets(DTCollation &coll, const char *fname,
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                       Item **args, uint nargs, uint flags, int item_sep)
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{
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  Item **arg, *safe_args[2];
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  LINT_INIT(safe_args[0]);
  LINT_INIT(safe_args[1]);
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  if (agg_item_collations(coll, fname, args, nargs, flags, item_sep))
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    return TRUE;

  /*
    For better error reporting: save the first and the second argument.
    We need this only if the the number of args is 3 or 2:
    - for a longer argument list, "Illegal mix of collations"
      doesn't display each argument's characteristics.
    - if nargs is 1, then this error cannot happen.
  */
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  LINT_INIT(safe_args[0]);
  LINT_INIT(safe_args[1]);
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  if (nargs >=2 && nargs <= 3)
  {
    safe_args[0]= args[0];
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    safe_args[1]= args[item_sep];
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  }

  THD *thd= current_thd;
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  Query_arena *arena, backup;
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  bool res= FALSE;
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  uint i;
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  /*
    In case we're in statement prepare, create conversion item
    in its memory: it will be reused on each execute.
  */
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  arena= thd->is_stmt_prepare() ? thd->activate_stmt_arena_if_needed(&backup)
                                : NULL;
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  for (i= 0, arg= args; i < nargs; i++, arg+= item_sep)
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  {
    Item* conv;
    uint32 dummy_offset;
    if (!String::needs_conversion(0, coll.collation,
                                  (*arg)->collation.collation,
                                  &dummy_offset))
      continue;

    if (!(conv= (*arg)->safe_charset_converter(coll.collation)))
    {
      if (nargs >=2 && nargs <= 3)
      {
        /* restore the original arguments for better error message */
        args[0]= safe_args[0];
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        args[item_sep]= safe_args[1];
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      }
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      my_coll_agg_error(args, nargs, fname, item_sep);
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      res= TRUE;
      break; // we cannot return here, we need to restore "arena".
    }
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    if ((*arg)->type() == Item::FIELD_ITEM)
      ((Item_field *)(*arg))->no_const_subst= 1;
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    /*
      If in statement prepare, then we create a converter for two
      constant items, do it once and then reuse it.
      If we're in execution of a prepared statement, arena is NULL,
      and the conv was created in runtime memory. This can be
      the case only if the argument is a parameter marker ('?'),
      because for all true constants the charset converter has already
      been created in prepare. In this case register the change for
      rollback.
    */
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    if (thd->is_stmt_prepare())
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      *arg= conv;
    else
      thd->change_item_tree(arg, conv);
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    /*
      We do not check conv->fixed, because Item_func_conv_charset which can
      be return by safe_charset_converter can't be fixed at creation
    */
    conv->fix_fields(thd, arg);
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  }
  if (arena)
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    thd->restore_active_arena(arena, &backup);
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  return res;
}


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void Item_ident_for_show::make_field(Send_field *tmp_field)
{
  tmp_field->table_name= tmp_field->org_table_name= table_name;
  tmp_field->db_name= db_name;
  tmp_field->col_name= tmp_field->org_col_name= field->field_name;
  tmp_field->charsetnr= field->charset()->number;
  tmp_field->length=field->field_length;
  tmp_field->type=field->type();
  tmp_field->flags= field->table->maybe_null ? 
    (field->flags & ~NOT_NULL_FLAG) : field->flags;
  tmp_field->decimals= 0;
}
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/**********************************************/

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Item_field::Item_field(Field *f)
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  :Item_ident(0, NullS, *f->table_name, f->field_name),
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   item_equal(0), no_const_subst(0),
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   have_privileges(0), any_privileges(0), fixed_as_field(0)
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{
  set_field(f);
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  /*
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    field_name and table_name should not point to garbage
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    if this item is to be reused
  */
  orig_table_name= orig_field_name= "";
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}

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Item_field::Item_field(THD *thd, Name_resolution_context *context_arg,
                       Field *f)
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  :Item_ident(context_arg, f->table->s->db.str, *f->table_name, f->field_name),
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   item_equal(0), no_const_subst(0),
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   have_privileges(0), any_privileges(0), fixed_as_field(0)
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{
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  /*
    We always need to provide Item_field with a fully qualified field
    name to avoid ambiguity when executing prepared statements like
    SELECT * from d1.t1, d2.t1; (assuming d1.t1 and d2.t1 have columns
    with same names).
    This is because prepared statements never deal with wildcards in
    select list ('*') and always fix fields using fully specified path
    (i.e. db.table.column).
    No check for OOM: if db_name is NULL, we'll just get
    "Field not found" error.
    We need to copy db_name, table_name and field_name because they must
    be allocated in the statement memory, not in table memory (the table
    structure can go away and pop up again between subsequent executions
    of a prepared statement).
  */
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  if (thd->stmt_arena->is_stmt_prepare_or_first_sp_execute())
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  {
    if (db_name)
      orig_db_name= thd->strdup(db_name);
    orig_table_name= thd->strdup(table_name);
    orig_field_name= thd->strdup(field_name);
    /*
      We don't restore 'name' in cleanup because it's not changed
      during execution. Still we need it to point to persistent
      memory if this item is to be reused.
    */
    name= (char*) orig_field_name;
  }
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  set_field(f);
}

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Item_field::Item_field(Name_resolution_context *context_arg,
                       const char *db_arg,const char *table_name_arg,
                       const char *field_name_arg)
  :Item_ident(context_arg, db_arg,table_name_arg,field_name_arg),
   field(0), result_field(0), item_equal(0), no_const_subst(0),
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   have_privileges(0), any_privileges(0), fixed_as_field(0)
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{
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  SELECT_LEX *select= current_thd->lex->current_select;
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  collation.set(DERIVATION_IMPLICIT);
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  if (select && select->parsing_place != IN_HAVING)
      select->select_n_where_fields++;
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}

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// Constructor need to process subselect with temporary tables (see Item)
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Item_field::Item_field(THD *thd, Item_field *item)
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  :Item_ident(thd, item),
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   field(item->field),
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   result_field(item->result_field),
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   item_equal(item->item_equal),
   no_const_subst(item->no_const_subst),
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   have_privileges(item->have_privileges),
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   any_privileges(item->any_privileges),
   fixed_as_field(item->fixed_as_field)
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{
  collation.set(DERIVATION_IMPLICIT);
}
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void Item_field::set_field(Field *field_par)
{
  field=result_field=field_par;			// for easy coding with fields
  maybe_null=field->maybe_null();
  decimals= field->decimals();
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  max_length= field_par->max_display_length();
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  table_name= *field_par->table_name;
  field_name= field_par->field_name;
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  db_name= field_par->table->s->db.str;
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  alias_name_used= field_par->table->alias_name_used;
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  unsigned_flag=test(field_par->flags & UNSIGNED_FLAG);
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  collation.set(field_par->charset(), field_par->derivation());
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  fixed= 1;
}


/*
  Reset this item to point to a field from the new temporary table.
  This is used when we create a new temporary table for each execution
  of prepared statement.
*/

void Item_field::reset_field(Field *f)
{
  set_field(f);
  /* 'name' is pointing at field->field_name of old field */
  name= (char*) f->field_name;
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}

const char *Item_ident::full_name() const
{
  char *tmp;
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  if (!table_name || !field_name)
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    return field_name ? field_name : name ? name : "tmp_field";
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  if (db_name && db_name[0])
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  {
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    tmp=(char*) sql_alloc((uint) strlen(db_name)+(uint) strlen(table_name)+
			  (uint) strlen(field_name)+3);
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    strxmov(tmp,db_name,".",table_name,".",field_name,NullS);
  }
  else
  {
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    if (table_name[0])
    {
      tmp= (char*) sql_alloc((uint) strlen(table_name) +
			     (uint) strlen(field_name) + 2);
      strxmov(tmp, table_name, ".", field_name, NullS);
    }
    else
      tmp= (char*) field_name;
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  }
  return tmp;
}

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void Item_ident::print(String *str)
{
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  THD *thd= current_thd;
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  char d_name_buff[MAX_ALIAS_NAME], t_name_buff[MAX_ALIAS_NAME];
  const char *d_name= db_name, *t_name= table_name;
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  if (lower_case_table_names== 1 ||
      (lower_case_table_names == 2 && !alias_name_used))
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  {
    if (table_name && table_name[0])
    {
      strmov(t_name_buff, table_name);
      my_casedn_str(files_charset_info, t_name_buff);
      t_name= t_name_buff;
    }
    if (db_name && db_name[0])
    {
      strmov(d_name_buff, db_name);
      my_casedn_str(files_charset_info, d_name_buff);
      d_name= d_name_buff;
    }
  }

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  if (!table_name || !field_name || !field_name[0])
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  {
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    const char *nm= (field_name && field_name[0]) ?
                      field_name : name ? name : "tmp_field";
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    append_identifier(thd, str, nm, (uint) strlen(nm));
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    return;
  }
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  if (db_name && db_name[0] && !alias_name_used)
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  {
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    if (!(cached_table && cached_table->belong_to_view &&
          cached_table->belong_to_view->compact_view_format))
    {
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      append_identifier(thd, str, d_name, (uint)strlen(d_name));
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      str->append('.');
    }
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    append_identifier(thd, str, t_name, (uint)strlen(t_name));
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    str->append('.');
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    append_identifier(thd, str, field_name, (uint)strlen(field_name));
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  }
  else
  {
    if (table_name[0])
    {
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      append_identifier(thd, str, t_name, (uint) strlen(t_name));
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      str->append('.');
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      append_identifier(thd, str, field_name, (uint) strlen(field_name));
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    }
    else
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      append_identifier(thd, str, field_name, (uint) strlen(field_name));
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  }
}

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/* ARGSUSED */
String *Item_field::val_str(String *str)
{
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  DBUG_ASSERT(fixed == 1);
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  if ((null_value=field->is_null()))
    return 0;
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  str->set_charset(str_value.charset());
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  return field->val_str(str,&str_value);
}

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double Item_field::val_real()
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{
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  DBUG_ASSERT(fixed == 1);
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  if ((null_value=field->is_null()))
    return 0.0;
  return field->val_real();
}

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longlong Item_field::val_int()
{
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  DBUG_ASSERT(fixed == 1);
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  if ((null_value=field->is_null()))
    return 0;
  return field->val_int();
}


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my_decimal *Item_field::val_decimal(my_decimal *decimal_value)
{
  if ((null_value= field->is_null()))
    return 0;
  return field->val_decimal(decimal_value);
}


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String *Item_field::str_result(String *str)
{
  if ((null_value=result_field->is_null()))
    return 0;
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  str->set_charset(str_value.charset());
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  return result_field->val_str(str,&str_value);
}

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bool Item_field::get_date(TIME *ltime,uint fuzzydate)
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{
  if ((null_value=field->is_null()) || field->get_date(ltime,fuzzydate))
  {
    bzero((char*) ltime,sizeof(*ltime));
    return 1;
  }
  return 0;
}

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bool Item_field::get_date_result(TIME *ltime,uint fuzzydate)
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{
  if ((null_value=result_field->is_null()) ||
      result_field->get_date(ltime,fuzzydate))
  {
    bzero((char*) ltime,sizeof(*ltime));
    return 1;
  }
  return 0;
}

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bool Item_field::get_time(TIME *ltime)
{
  if ((null_value=field->is_null()) || field->get_time(ltime))
  {
    bzero((char*) ltime,sizeof(*ltime));
    return 1;
  }
  return 0;
}

double Item_field::val_result()
{
  if ((null_value=result_field->is_null()))
    return 0.0;
  return result_field->val_real();
}

longlong Item_field::val_int_result()
{
  if ((null_value=result_field->is_null()))
    return 0;
  return result_field->val_int();
}

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my_decimal *Item_field::val_decimal_result(my_decimal *decimal_value)
{
  if ((null_value= result_field->is_null()))
    return 0;
  return result_field->val_decimal(decimal_value);
}


bool Item_field::val_bool_result()
{
  if ((null_value= result_field->is_null()))
    return FALSE;
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  switch (result_field->result_type()) {
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  case INT_RESULT:
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    return result_field->val_int() != 0;
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  case DECIMAL_RESULT:
  {
    my_decimal decimal_value;
    my_decimal *val= result_field->val_decimal(&decimal_value);
    if (val)
      return !my_decimal_is_zero(val);
    return 0;
  }
  case REAL_RESULT:
  case STRING_RESULT:
    return result_field->val_real() != 0.0;
  case ROW_RESULT:
  default:
    DBUG_ASSERT(0);
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    return 0;                                   // Shut up compiler
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  }
}


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bool Item_field::eq(const Item *item, bool binary_cmp) const
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{
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  if (item->type() != FIELD_ITEM)
    return 0;
  
  Item_field *item_field= (Item_field*) item;
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  if (item_field->field && field)
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    return item_field->field == field;
  /*
    We may come here when we are trying to find a function in a GROUP BY
    clause from the select list.
    In this case the '100 % correct' way to do this would be to first
    run fix_fields() on the GROUP BY item and then retry this function, but
    I think it's better to relax the checking a bit as we will in
    most cases do the correct thing by just checking the field name.
    (In cases where we would choose wrong we would have to generate a
    ER_NON_UNIQ_ERROR).
  */
  return (!my_strcasecmp(system_charset_info, item_field->name,
			 field_name) &&
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	  (!item_field->table_name || !table_name ||
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	   (!my_strcasecmp(table_alias_charset, item_field->table_name,
			   table_name) &&
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	    (!item_field->db_name || !db_name ||
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	     (item_field->db_name && !strcmp(item_field->db_name,
					     db_name))))));
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}

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table_map Item_field::used_tables() const
{
  if (field->table->const_table)
    return 0;					// const item
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  return (depended_from ? OUTER_REF_TABLE_BIT : field->table->map);
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}

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Item *Item_field::get_tmp_table_item(THD *thd)
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{
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  Item_field *new_item= new Item_field(thd, this);
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  if (new_item)
    new_item->field= new_item->result_field;
  return new_item;
}
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/*
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  Create an item from a string we KNOW points to a valid longlong
  end \0 terminated number string.
  This is always 'signed'. Unsigned values are created with Item_uint()
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*/

Item_int::Item_int(const char *str_arg, uint length)
{
  char *end_ptr= (char*) str_arg + length;
  int error;
  value= my_strtoll10(str_arg, &end_ptr, &error);
  max_length= (uint) (end_ptr - str_arg);
  name= (char*) str_arg;
  fixed= 1;
}


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my_decimal *Item_int::val_decimal(my_decimal *decimal_value)
{
  int2my_decimal(E_DEC_FATAL_ERROR, value, unsigned_flag, decimal_value);
  return decimal_value;
}

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String *Item_int::val_str(String *str)
{
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  // following assert is redundant, because fixed=1 assigned in constructor
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  DBUG_ASSERT(fixed == 1);
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  str->set(value, &my_charset_bin);
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  return str;
}

void Item_int::print(String *str)
{
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  // my_charset_bin is good enough for numbers
  str_value.set(value, &my_charset_bin);
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  str->append(str_value);
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}

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Item_uint::Item_uint(const char *str_arg, uint length):
  Item_int(str_arg, length)
{
  unsigned_flag= 1;
}


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Item_uint::Item_uint(const char *str_arg, longlong i, uint length):
  Item_int(str_arg, i, length)
{
  unsigned_flag= 1;
}


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String *Item_uint::val_str(String *str)
{
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  // following assert is redundant, because fixed=1 assigned in constructor
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  DBUG_ASSERT(fixed == 1);
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  str->set((ulonglong) value, &my_charset_bin);
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  return str;
}

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void Item_uint::print(String *str)
{
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  // latin1 is good enough for numbers
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  str_value.set((ulonglong) value, default_charset());
  str->append(str_value);
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}

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Item_decimal::Item_decimal(const char *str_arg, uint length,
                           CHARSET_INFO *charset)
{
  str2my_decimal(E_DEC_FATAL_ERROR, str_arg, length, charset, &decimal_value);
  name= (char*) str_arg;
  decimals= (uint8) decimal_value.frac;
  fixed= 1;
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  max_length= my_decimal_precision_to_length(decimal_value.intg + decimals,
                                             decimals, unsigned_flag);
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}

Item_decimal::Item_decimal(longlong val, bool unsig)
{
  int2my_decimal(E_DEC_FATAL_ERROR, val, unsig, &decimal_value);
  decimals= (uint8) decimal_value.frac;
  fixed= 1;
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  max_length= my_decimal_precision_to_length(decimal_value.intg + decimals,
                                             decimals, unsigned_flag);
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}


Item_decimal::Item_decimal(double val, int precision, int scale)
{
  double2my_decimal(E_DEC_FATAL_ERROR, val, &decimal_value);
  decimals= (uint8) decimal_value.frac;
  fixed= 1;
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  max_length= my_decimal_precision_to_length(decimal_value.intg + decimals,
                                             decimals, unsigned_flag);
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}


Item_decimal::Item_decimal(const char *str, const my_decimal *val_arg,
                           uint decimal_par, uint length)
{
  my_decimal2decimal(val_arg, &decimal_value);
  name= (char*) str;
  decimals= (uint8) decimal_par;
  max_length= length;
  fixed= 1;
}


Item_decimal::Item_decimal(my_decimal *value_par)
{
  my_decimal2decimal(value_par, &decimal_value);
  decimals= (uint8) decimal_value.frac;
  fixed= 1;
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  max_length= my_decimal_precision_to_length(decimal_value.intg + decimals,
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                                             decimals, unsigned_flag);
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}


Item_decimal::Item_decimal(const char *bin, int precision, int scale)
{
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  binary2my_decimal(E_DEC_FATAL_ERROR, bin,
                    &decimal_value, precision, scale);
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  decimals= (uint8) decimal_value.frac;
  fixed= 1;
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  max_length= my_decimal_precision_to_length(precision, decimals,
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                                             unsigned_flag);
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}


longlong Item_decimal::val_int()
{
  longlong result;
  my_decimal2int(E_DEC_FATAL_ERROR, &decimal_value, unsigned_flag, &result);
  return result;
}

double Item_decimal::val_real()
{
  double result;
  my_decimal2double(E_DEC_FATAL_ERROR, &decimal_value, &result);
  return result;
}

String *Item_decimal::val_str(String *result)
{
  result->set_charset(&my_charset_bin);
  my_decimal2string(E_DEC_FATAL_ERROR, &decimal_value, 0, 0, 0, result);
  return result;
}

void Item_decimal::print(String *str)
{
  my_decimal2string(E_DEC_FATAL_ERROR, &decimal_value, 0, 0, 0, &str_value);
  str->append(str_value);
}


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bool Item_decimal::eq(const Item *item, bool binary_cmp) const
{
  if (type() == item->type() && item->basic_const_item())
  {
    /*
      We need to cast off const to call val_decimal(). This should
      be OK for a basic constant. Additionally, we can pass 0 as
      a true decimal constant will return its internal decimal
      storage and ignore the argument.
    */
    Item *arg= (Item*) item;
    my_decimal *value= arg->val_decimal(0);
    return !my_decimal_cmp(&decimal_value, value);
  }
  return 0;
}


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void Item_decimal::set_decimal_value(my_decimal *value_par)
{
  my_decimal2decimal(value_par, &decimal_value);
  decimals= (uint8) decimal_value.frac;
  unsigned_flag= !decimal_value.sign();
  max_length= my_decimal_precision_to_length(decimal_value.intg + decimals,
                                             decimals, unsigned_flag);
}


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String *Item_float::val_str(String *str)
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{
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  // following assert is redundant, because fixed=1 assigned in constructor
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  DBUG_ASSERT(fixed == 1);
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  str->set_real(value,decimals,&my_charset_bin);
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  return str;
}

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my_decimal *Item_float::val_decimal(my_decimal *decimal_value)
{
  // following assert is redundant, because fixed=1 assigned in constructor
  DBUG_ASSERT(fixed == 1);
  double2my_decimal(E_DEC_FATAL_ERROR, value, decimal_value);
  return (decimal_value);
}


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void Item_string::print(String *str)
{
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  str->append('_');
  str->append(collation.collation->csname);
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  str->append('\'');
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  str_value.print(str);
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  str->append('\'');
}

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double Item_string::val_real()
{
  DBUG_ASSERT(fixed == 1);
  int error;
  char *end, *org_end;
  double tmp;
  CHARSET_INFO *cs= str_value.charset();

  org_end= (char*) str_value.ptr() + str_value.length();
  tmp= my_strntod(cs, (char*) str_value.ptr(), str_value.length(), &end,
                  &error);
  if (error || (end != org_end && !check_if_only_end_space(cs, end, org_end)))
  {
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    /*
      We can use str_value.ptr() here as Item_string is gurantee to put an
      end \0 here.
    */
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    push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                        ER_TRUNCATED_WRONG_VALUE,
                        ER(ER_TRUNCATED_WRONG_VALUE), "DOUBLE",
                        str_value.ptr());
  }
  return tmp;
}


longlong Item_string::val_int()
{
  DBUG_ASSERT(fixed == 1);
  int err;
  longlong tmp;
  char *end= (char*) str_value.ptr()+ str_value.length();
  char *org_end= end;
  CHARSET_INFO *cs= str_value.charset();

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  tmp= (*(cs->cset->strtoll10))(cs, str_value.ptr(), &end, &err);
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  /*
    TODO: Give error if we wanted a signed integer and we got an unsigned
    one
  */
  if (err > 0 ||
      (end != org_end && !check_if_only_end_space(cs, end, org_end)))
  {
    push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                        ER_TRUNCATED_WRONG_VALUE,
                        ER(ER_TRUNCATED_WRONG_VALUE), "INTEGER",
                        str_value.ptr());
  }
  return tmp;
}


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my_decimal *Item_string::val_decimal(my_decimal *decimal_value)
{
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  return val_decimal_from_string(decimal_value);
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}


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bool Item_null::eq(const Item *item, bool binary_cmp) const
{ return item->type() == type(); }
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double Item_null::val_real()
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{
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  // following assert is redundant, because fixed=1 assigned in constructor
  DBUG_ASSERT(fixed == 1);
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  null_value=1;
  return 0.0;
}
longlong Item_null::val_int()
{
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  // following assert is redundant, because fixed=1 assigned in constructor
  DBUG_ASSERT(fixed == 1);
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  null_value=1;
  return 0;
}
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/* ARGSUSED */
String *Item_null::val_str(String *str)
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{
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  // following assert is redundant, because fixed=1 assigned in constructor
  DBUG_ASSERT(fixed == 1);
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  null_value=1;
  return 0;
}
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my_decimal *Item_null::val_decimal(my_decimal *decimal_value)
{
  return 0;
}

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Item *Item_null::safe_charset_converter(CHARSET_INFO *tocs)
{
  collation.set(tocs);
  return this;
}

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/*********************** Item_param related ******************************/

/* 
  Default function of Item_param::set_param_func, so in case
  of malformed packet the server won't SIGSEGV
*/

static void
default_set_param_func(Item_param *param,
                       uchar **pos __attribute__((unused)),
                       ulong len __attribute__((unused)))
{
  param->set_null();
}

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Item_param::Item_param(unsigned pos_in_query_arg) :
  state(NO_VALUE),
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  item_result_type(STRING_RESULT),
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  /* Don't pretend to be a literal unless value for this item is set. */
  item_type(PARAM_ITEM),
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  param_type(MYSQL_TYPE_VARCHAR),
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  pos_in_query(pos_in_query_arg),
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  set_param_func(default_set_param_func)
{
  name= (char*) "?";
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  /* 
    Since we can't say whenever this item can be NULL or cannot be NULL
    before mysql_stmt_execute(), so we assuming that it can be NULL until
    value is set.
  */
  maybe_null= 1;
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  cnvitem= new Item_string("", 0, &my_charset_bin, DERIVATION_COERCIBLE);
  cnvstr.set(cnvbuf, sizeof(cnvbuf), &my_charset_bin);
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}
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void Item_param::set_null()
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{
  DBUG_ENTER("Item_param::set_null");
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  /* These are cleared after each execution by reset() method */
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  null_value= 1;
  /* 
    Because of NULL and string values we need to set max_length for each new
    placeholder value: user can submit NULL for any placeholder type, and 
    string length can be different in each execution.
  */
  max_length= 0;
  decimals= 0;
  state= NULL_VALUE;
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  item_type= Item::NULL_ITEM;
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  DBUG_VOID_RETURN;
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}

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void Item_param::set_int(longlong i, uint32 max_length_arg)
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{
  DBUG_ENTER("Item_param::set_int");
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  value.integer= (longlong) i;
  state= INT_VALUE;
  max_length= max_length_arg;
  decimals= 0;
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  maybe_null= 0;
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  DBUG_VOID_RETURN;
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}

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void Item_param::set_double(double d)
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{
  DBUG_ENTER("Item_param::set_double");
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  value.real= d;
  state= REAL_VALUE;
  max_length= DBL_DIG + 8;
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  decimals= NOT_FIXED_DEC;
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  maybe_null= 0;
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  DBUG_VOID_RETURN;
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}


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/*
  Set decimal parameter value from string.

  SYNOPSIS
    set_decimal()
      str    - character string
      length - string length

  NOTE
    as we use character strings to send decimal values in
    binary protocol, we use str2my_decimal to convert it to
    internal decimal value.
*/
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void Item_param::set_decimal(const char *str, ulong length)
{
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  char *end;
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  DBUG_ENTER("Item_param::set_decimal");

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  end= (char*) str+length;
  str2my_decimal(E_DEC_FATAL_ERROR, str, &decimal_value, &end);
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  state= DECIMAL_VALUE;
  decimals= decimal_value.frac;
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  max_length= my_decimal_precision_to_length(decimal_value.precision(),
                                             decimals, unsigned_flag);
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  maybe_null= 0;
  DBUG_VOID_RETURN;
}


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/*
  Set parameter value from TIME value.

  SYNOPSIS
    set_time()
      tm             - datetime value to set (time_type is ignored)
      type           - type of datetime value
      max_length_arg - max length of datetime value as string

  NOTE
    If we value to be stored is not normalized, zero value will be stored
    instead and proper warning will be produced. This function relies on
    the fact that even wrong value sent over binary protocol fits into
    MAX_DATE_STRING_REP_LENGTH buffer.
*/
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void Item_param::set_time(TIME *tm, timestamp_type time_type,
                          uint32 max_length_arg)
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{ 
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  DBUG_ENTER("Item_param::set_time");
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  value.time= *tm;
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  value.time.time_type= time_type;
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  if (value.time.year > 9999 || value.time.month > 12 ||
      value.time.day > 31 ||
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      time_type != MYSQL_TIMESTAMP_TIME && value.time.hour > 23 ||
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      value.time.minute > 59 || value.time.second > 59)
  {
    char buff[MAX_DATE_STRING_REP_LENGTH];
    uint length= my_TIME_to_str(&value.time, buff);
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    make_truncated_value_warning(current_thd, buff, length, time_type, 0);
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    set_zero_time(&value.time, MYSQL_TIMESTAMP_ERROR);
  }

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  state= TIME_VALUE;
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  maybe_null= 0;
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  max_length= max_length_arg;
  decimals= 0;
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  DBUG_VOID_RETURN;
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}

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bool Item_param::set_str(const char *str, ulong length)
{
  DBUG_ENTER("Item_param::set_str");
  /*
    Assign string with no conversion: data is converted only after it's
    been written to the binary log.
  */
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  uint dummy_errors;
  if (str_value.copy(str, length, &my_charset_bin, &my_charset_bin,
                     &dummy_errors))
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    DBUG_RETURN(TRUE);
  state= STRING_VALUE;
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  max_length= length;
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  maybe_null= 0;
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  /* max_length and decimals are set after charset conversion */
  /* sic: str may be not null-terminated, don't add DBUG_PRINT here */
  DBUG_RETURN(FALSE);
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}


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bool Item_param::set_longdata(const char *str, ulong length)
{
  DBUG_ENTER("Item_param::set_longdata");

  /*
    If client character set is multibyte, end of long data packet
    may hit at the middle of a multibyte character.  Additionally,
    if binary log is open we must write long data value to the
    binary log in character set of client. This is why we can't
    convert long data to connection character set as it comes
    (here), and first have to concatenate all pieces together,
    write query to the binary log and only then perform conversion.
  */
  if (str_value.append(str, length, &my_charset_bin))
    DBUG_RETURN(TRUE);
  state= LONG_DATA_VALUE;
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  maybe_null= 0;
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  DBUG_RETURN(FALSE);
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}


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/*
  Set parameter value from user variable value.

  SYNOPSIS
   set_from_user_var
     thd   Current thread
     entry User variable structure (NULL means use NULL value)

  RETURN
    0 OK
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    1 Out of memory
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*/

bool Item_param::set_from_user_var(THD *thd, const user_var_entry *entry)
{
  DBUG_ENTER("Item_param::set_from_user_var");
  if (entry && entry->value)
  {
    item_result_type= entry->type;
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    switch (entry->type) {
    case REAL_RESULT:
      set_double(*(double*)entry->value);
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      item_type= Item::REAL_ITEM;
      item_result_type= REAL_RESULT;
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      break;
    case INT_RESULT:
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      set_int(*(longlong*)entry->value, MY_INT64_NUM_DECIMAL_DIGITS);
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      item_type= Item::INT_ITEM;
      item_result_type= INT_RESULT;
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      break;
    case STRING_RESULT:
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    {
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      CHARSET_INFO *fromcs= entry->collation.collation;
      CHARSET_INFO *tocs= thd->variables.collation_connection;
      uint32 dummy_offset;

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      value.cs_info.character_set_of_placeholder= 
        value.cs_info.character_set_client= fromcs;
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      /*
        Setup source and destination character sets so that they
        are different only if conversion is necessary: this will
        make later checks easier.
      */
      value.cs_info.final_character_set_of_str_value=
        String::needs_conversion(0, fromcs, tocs, &dummy_offset) ?
        tocs : fromcs;
      /*
        Exact value of max_length is not known unless data is converted to
        charset of connection, so we have to set it later.
      */
      item_type= Item::STRING_ITEM;
      item_result_type= STRING_RESULT;

      if (set_str((const char *)entry->value, entry->length))
        DBUG_RETURN(1);
      break;
    }
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    case DECIMAL_RESULT:
    {
      const my_decimal *ent_value= (const my_decimal *)entry->value;
      my_decimal2decimal(ent_value, &decimal_value);
      state= DECIMAL_VALUE;
      decimals= ent_value->frac;
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      max_length= my_decimal_precision_to_length(ent_value->precision(),
                                                 decimals, unsigned_flag);
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      break;
    }
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    default:
      DBUG_ASSERT(0);
      set_null();
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    }
  }
  else
    set_null();

  DBUG_RETURN(0);
}

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/*
    Resets parameter after execution.
  
  SYNOPSIS
     Item_param::reset()
 
  NOTES
    We clear null_value here instead of setting it in set_* methods, 
    because we want more easily handle case for long data.
*/

void Item_param::reset()
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{
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  DBUG_ENTER("Item_param::reset");
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  /* Shrink string buffer if it's bigger than max possible CHAR column */
  if (str_value.alloced_length() > MAX_CHAR_WIDTH)
    str_value.free();
  else
    str_value.length(0);
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  str_value_ptr.length(0);
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  /*
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    We must prevent all charset conversions until data has been written
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    to the binary log.
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  */
  str_value.set_charset(&my_charset_bin);
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  collation.set(&my_charset_bin, DERIVATION_COERCIBLE);
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  state= NO_VALUE;
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  maybe_null= 1;
  null_value= 0;
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  /*
    Don't reset item_type to PARAM_ITEM: it's only needed to guard
    us from item optimizations at prepare stage, when item doesn't yet
    contain a literal of some kind.
    In all other cases when this object is accessed its value is
    set (this assumption is guarded by 'state' and
    DBUG_ASSERTS(state != NO_VALUE) in all Item_param::get_*
    methods).
  */
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  DBUG_VOID_RETURN;
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}


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int Item_param::save_in_field(Field *field, bool no_conversions)
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{
  field->set_notnull();
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  switch (state) {
  case INT_VALUE:
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    return field->store(value.integer, unsigned_flag);
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  case REAL_VALUE:
    return field->store(value.real);
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  case DECIMAL_VALUE:
    return field->store_decimal(&decimal_value);
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  case TIME_VALUE:
    field->store_time(&value.time, value.time.time_type);
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    return 0;
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
    return field->store(str_value.ptr(), str_value.length(),
                        str_value.charset());
  case NULL_VALUE:
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    return set_field_to_null_with_conversions(field, no_conversions);
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  case NO_VALUE:
  default:
    DBUG_ASSERT(0);
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  }
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  return 1;
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}

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bool Item_param::get_time(TIME *res)
{
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  if (state == TIME_VALUE)
  {
    *res= value.time;
    return 0;
  }
  /*
    If parameter value isn't supplied assertion will fire in val_str()
    which is called from Item::get_time().
  */
  return Item::get_time(res);
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}
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bool Item_param::get_date(TIME *res, uint fuzzydate)
{
  if (state == TIME_VALUE)
  {
    *res= value.time;
    return 0;
  }
  return Item::get_date(res, fuzzydate);
}


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double Item_param::val_real()
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{
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  switch (state) {
  case REAL_VALUE:
    return value.real;
  case INT_VALUE:
    return (double) value.integer;
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  case DECIMAL_VALUE:
  {
    double result;
    my_decimal2double(E_DEC_FATAL_ERROR, &decimal_value, &result);
    return result;
  }
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
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  {
    int dummy_err;
    char *end_not_used;
    return my_strntod(str_value.charset(), (char*) str_value.ptr(),
                      str_value.length(), &end_not_used, &dummy_err);
  }
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  case TIME_VALUE:
    /*
      This works for example when user says SELECT ?+0.0 and supplies
      time value for the placeholder.
    */
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    return ulonglong2double(TIME_to_ulonglong(&value.time));
2708
  case NULL_VALUE:
2709
    return 0.0;
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  default:
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    DBUG_ASSERT(0);
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  }
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  return 0.0;
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} 

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longlong Item_param::val_int() 
{ 
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  switch (state) {
  case REAL_VALUE:
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    return (longlong) rint(value.real);
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  case INT_VALUE:
    return value.integer;
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  case DECIMAL_VALUE:
  {
    longlong i;
    my_decimal2int(E_DEC_FATAL_ERROR, &decimal_value, unsigned_flag, &i);
    return i;
  }
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
    {
      int dummy_err;
      return my_strntoll(str_value.charset(), str_value.ptr(),
                         str_value.length(), 10, (char**) 0, &dummy_err);
    }
  case TIME_VALUE:
    return (longlong) TIME_to_ulonglong(&value.time);
  case NULL_VALUE:
    return 0; 
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  default:
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    DBUG_ASSERT(0);
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  }
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  return 0;
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}

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my_decimal *Item_param::val_decimal(my_decimal *dec)
{
  switch (state) {
  case DECIMAL_VALUE:
    return &decimal_value;
  case REAL_VALUE:
    double2my_decimal(E_DEC_FATAL_ERROR, value.real, dec);
    return dec;
  case INT_VALUE:
    int2my_decimal(E_DEC_FATAL_ERROR, value.integer, unsigned_flag, dec);
    return dec;
  case STRING_VALUE:
  case LONG_DATA_VALUE:
    string2my_decimal(E_DEC_FATAL_ERROR, &str_value, dec);
    return dec;
  case TIME_VALUE:
  {
    longlong i= (longlong) TIME_to_ulonglong(&value.time);
    int2my_decimal(E_DEC_FATAL_ERROR, i, 0, dec);
    return dec;
  }
  case NULL_VALUE:
    return 0; 
  default:
    DBUG_ASSERT(0);
  }
  return 0;
}


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String *Item_param::val_str(String* str) 
{ 
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  switch (state) {
  case STRING_VALUE:
  case LONG_DATA_VALUE:
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    return &str_value_ptr;
2784
  case REAL_VALUE:
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    str->set_real(value.real, NOT_FIXED_DEC, &my_charset_bin);
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    return str;
  case INT_VALUE:
    str->set(value.integer, &my_charset_bin);
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    return str;
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  case DECIMAL_VALUE:
    if (my_decimal2string(E_DEC_FATAL_ERROR, &decimal_value,
                          0, 0, 0, str) <= 1)
      return str;
    return NULL;
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  case TIME_VALUE:
  {
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    if (str->reserve(MAX_DATE_STRING_REP_LENGTH))
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      break;
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    str->length((uint) my_TIME_to_str(&value.time, (char*) str->ptr()));
    str->set_charset(&my_charset_bin);
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    return str;
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  }
  case NULL_VALUE:
    return NULL; 
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  default:
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    DBUG_ASSERT(0);
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  }
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  return str;
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}
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/*
  Return Param item values in string format, for generating the dynamic 
  query used in update/binary logs
2814 2815
  TODO: change interface and implementation to fill log data in place
  and avoid one more memcpy/alloc between str and log string.
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*/

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const String *Item_param::query_val_str(String* str) const
2819
{
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  switch (state) {
  case INT_VALUE:
    str->set(value.integer, &my_charset_bin);
    break;
  case REAL_VALUE:
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    str->set_real(value.real, NOT_FIXED_DEC, &my_charset_bin);
2826
    break;
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  case DECIMAL_VALUE:
    if (my_decimal2string(E_DEC_FATAL_ERROR, &decimal_value,
                          0, 0, 0, str) > 1)
      return &my_null_string;
    break;
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  case TIME_VALUE:
2833
    {
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      char *buf, *ptr;
      str->length(0);
      /*
        TODO: in case of error we need to notify replication
        that binary log contains wrong statement 
      */
2840
      if (str->reserve(MAX_DATE_STRING_REP_LENGTH+3))
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        break; 

      /* Create date string inplace */
      buf= str->c_ptr_quick();
      ptr= buf;
      *ptr++= '\'';
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      ptr+= (uint) my_TIME_to_str(&value.time, ptr);
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      *ptr++= '\'';
      str->length((uint32) (ptr - buf));
      break;
2851
    }
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
2854
    {
2855
      str->length(0);
2856
      append_query_string(value.cs_info.character_set_client, &str_value, str);
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      break;
2858
    }
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  case NULL_VALUE:
    return &my_null_string;
  default:
    DBUG_ASSERT(0);
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  }
  return str;
}
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/*
  Convert string from client character set to the character set of
  connection.
*/

bool Item_param::convert_str_value(THD *thd)
{
  bool rc= FALSE;
  if (state == STRING_VALUE || state == LONG_DATA_VALUE)
  {
    /*
      Check is so simple because all charsets were set up properly
      in setup_one_conversion_function, where typecode of
      placeholder was also taken into account: the variables are different
      here only if conversion is really necessary.
    */
    if (value.cs_info.final_character_set_of_str_value !=
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        value.cs_info.character_set_of_placeholder)
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    {
      rc= thd->convert_string(&str_value,
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                              value.cs_info.character_set_of_placeholder,
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                              value.cs_info.final_character_set_of_str_value);
    }
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    else
      str_value.set_charset(value.cs_info.final_character_set_of_str_value);
    /* Here str_value is guaranteed to be in final_character_set_of_str_value */

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    max_length= str_value.length();
    decimals= 0;
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    /*
      str_value_ptr is returned from val_str(). It must be not alloced
      to prevent it's modification by val_str() invoker.
    */
    str_value_ptr.set(str_value.ptr(), str_value.length(),
                      str_value.charset());
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    /* Synchronize item charset with value charset */
    collation.set(str_value.charset(), DERIVATION_COERCIBLE);
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  }
  return rc;
}

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bool Item_param::basic_const_item() const
{
  if (state == NO_VALUE || state == TIME_VALUE)
    return FALSE;
  return TRUE;
}

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2918
Item *
2919
Item_param::clone_item()
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{
  /* see comments in the header file */
  switch (state) {
  case NULL_VALUE:
    return new Item_null(name);
  case INT_VALUE:
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    return (unsigned_flag ?
            new Item_uint(name, value.integer, max_length) :
            new Item_int(name, value.integer, max_length));
2929
  case REAL_VALUE:
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    return new Item_float(name, value.real, decimals, max_length);
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
    return new Item_string(name, str_value.c_ptr_quick(), str_value.length(),
                           str_value.charset());
  case TIME_VALUE:
    break;
  case NO_VALUE:
  default:
    DBUG_ASSERT(0);
  };
  return 0;
}


bool
Item_param::eq(const Item *arg, bool binary_cmp) const
{
  Item *item;
  if (!basic_const_item() || !arg->basic_const_item() || arg->type() != type())
    return FALSE;
  /*
    We need to cast off const to call val_int(). This should be OK for
    a basic constant.
  */
  item= (Item*) arg;

  switch (state) {
  case NULL_VALUE:
    return TRUE;
  case INT_VALUE:
    return value.integer == item->val_int() &&
           unsigned_flag == item->unsigned_flag;
  case REAL_VALUE:
2964
    return value.real == item->val_real();
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
    if (binary_cmp)
      return !stringcmp(&str_value, &item->str_value);
    return !sortcmp(&str_value, &item->str_value, collation.collation);
  default:
    break;
  }
  return FALSE;
}

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/* End of Item_param related */

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void Item_param::print(String *str)
{
  if (state == NO_VALUE)
  {
    str->append('?');
  }
  else
  {
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    char buffer[STRING_BUFFER_USUAL_SIZE];
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    String tmp(buffer, sizeof(buffer), &my_charset_bin);
    const String *res;
    res= query_val_str(&tmp);
    str->append(*res);
  }
}


/****************************************************************************
  Item_copy_string
****************************************************************************/
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void Item_copy_string::copy()
{
  String *res=item->val_str(&str_value);
  if (res && res != &str_value)
    str_value.copy(*res);
  null_value=item->null_value;
}

/* ARGSUSED */
String *Item_copy_string::val_str(String *str)
{
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  // Item_copy_string is used without fix_fields call
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  if (null_value)
    return (String*) 0;
  return &str_value;
}

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my_decimal *Item_copy_string::val_decimal(my_decimal *decimal_value)
{
  // Item_copy_string is used without fix_fields call
  if (null_value)
    return 0;
  string2my_decimal(E_DEC_FATAL_ERROR, &str_value, decimal_value);
  return (decimal_value);
}



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int Item_copy_string::save_in_field(Field *field, bool no_conversions)
{
  if (null_value)
    return set_field_to_null(field);
  field->set_notnull();
  return field->store(str_value.ptr(),str_value.length(),
		      collation.collation);
}

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/*
3038
  Functions to convert item to field (for send_fields)
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*/

/* ARGSUSED */
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bool Item::fix_fields(THD *thd, Item **ref)
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{
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  // We do not check fields which are fixed during construction
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  DBUG_ASSERT(fixed == 0 || basic_const_item());
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  fixed= 1;
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  return FALSE;
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}

3051
double Item_ref_null_helper::val_real()
3052
{
3053
  DBUG_ASSERT(fixed == 1);
3054
  double tmp= (*ref)->val_result();
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  owner->was_null|= null_value= (*ref)->null_value;
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  return tmp;
}
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longlong Item_ref_null_helper::val_int()
{
3062
  DBUG_ASSERT(fixed == 1);
3063
  longlong tmp= (*ref)->val_int_result();
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  owner->was_null|= null_value= (*ref)->null_value;
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  return tmp;
}
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my_decimal *Item_ref_null_helper::val_decimal(my_decimal *decimal_value)
{
  DBUG_ASSERT(fixed == 1);
  my_decimal *val= (*ref)->val_decimal_result(decimal_value);
  owner->was_null|= null_value= (*ref)->null_value;
  return val;
}


bool Item_ref_null_helper::val_bool()
{
  DBUG_ASSERT(fixed == 1);
  bool val= (*ref)->val_bool_result();
  owner->was_null|= null_value= (*ref)->null_value;
  return val;
}


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String* Item_ref_null_helper::val_str(String* s)
{
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  DBUG_ASSERT(fixed == 1);
3090
  String* tmp= (*ref)->str_result(s);
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  owner->was_null|= null_value= (*ref)->null_value;
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  return tmp;
}
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3096
bool Item_ref_null_helper::get_date(TIME *ltime, uint fuzzydate)
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{  
  return (owner->was_null|= null_value= (*ref)->get_date(ltime, fuzzydate));
}
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/*
3103
  Mark item and SELECT_LEXs as dependent if item was resolved in outer SELECT
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  SYNOPSIS
    mark_as_dependent()
3107
    thd - thread handler
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    last - select from which current item depend
    current  - current select
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    resolved_item - item which was resolved in outer SELECT(for warning)
    mark_item - item which should be marked (can be differ in case of
                substitution)
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*/

3115
static void mark_as_dependent(THD *thd, SELECT_LEX *last, SELECT_LEX *current,
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                              Item_ident *resolved_item,
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                              Item_ident *mark_item)
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{
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  const char *db_name= (resolved_item->db_name ?
                        resolved_item->db_name : "");
  const char *table_name= (resolved_item->table_name ?
                           resolved_item->table_name : "");
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  /* store pointer on SELECT_LEX from which item is dependent */
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  if (mark_item)
    mark_item->depended_from= last;
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  current->mark_as_dependent(last);
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  if (thd->lex->describe & DESCRIBE_EXTENDED)
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  {
    char warn_buff[MYSQL_ERRMSG_SIZE];
    sprintf(warn_buff, ER(ER_WARN_FIELD_RESOLVED),
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            db_name, (db_name[0] ? "." : ""),
            table_name, (table_name [0] ? "." : ""),
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            resolved_item->field_name,
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	    current->select_number, last->select_number);
    push_warning(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
		 ER_WARN_FIELD_RESOLVED, warn_buff);
  }
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}


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/*
  Mark range of selects and resolved identifier (field/reference) item as
  dependent

  SYNOPSIS
    mark_select_range_as_dependent()
    thd           - thread handler
    last_select   - select where resolved_item was resolved
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    current_sel   - current select (select where resolved_item was placed)
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    found_field   - field which was found during resolving
    found_item    - Item which was found during resolving (if resolved
                    identifier belongs to VIEW)
    resolved_item - Identifier which was resolved

  NOTE:
    We have to mark all items between current_sel (including) and
    last_select (excluding) as dependend (select before last_select should
    be marked with actual table mask used by resolved item, all other with
    OUTER_REF_TABLE_BIT) and also write dependence information to Item of
    resolved identifier.
*/

void mark_select_range_as_dependent(THD *thd,
                                    SELECT_LEX *last_select,
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                                    SELECT_LEX *current_sel,
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                                    Field *found_field, Item *found_item,
                                    Item_ident *resolved_item)
{
  /*
    Go from current SELECT to SELECT where field was resolved (it
    have to be reachable from current SELECT, because it was already
    done once when we resolved this field and cached result of
    resolving)
  */
  SELECT_LEX *previous_select= current_sel;
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  for (; previous_select->outer_select() != last_select;
       previous_select= previous_select->outer_select())
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  {
    Item_subselect *prev_subselect_item=
      previous_select->master_unit()->item;
    prev_subselect_item->used_tables_cache|= OUTER_REF_TABLE_BIT;
    prev_subselect_item->const_item_cache= 0;
  }
  {
    Item_subselect *prev_subselect_item=
      previous_select->master_unit()->item;
    Item_ident *dependent= resolved_item;
    if (found_field == view_ref_found)
    {
      Item::Type type= found_item->type();
      prev_subselect_item->used_tables_cache|=
        found_item->used_tables();
      dependent= ((type == Item::REF_ITEM || type == Item::FIELD_ITEM) ?
                  (Item_ident*) found_item :
                  0);
    }
    else
      prev_subselect_item->used_tables_cache|=
        found_field->table->map;
    prev_subselect_item->const_item_cache= 0;
    mark_as_dependent(thd, last_select, current_sel, resolved_item,
                      dependent);
  }
}
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/*
  Search a GROUP BY clause for a field with a certain name.

  SYNOPSIS
    find_field_in_group_list()
    find_item  the item being searched for
    group_list GROUP BY clause

  DESCRIPTION
    Search the GROUP BY list for a column named as find_item. When searching
    preference is given to columns that are qualified with the same table (and
    database) name as the one being searched for.

  RETURN
    - the found item on success
    - NULL if find_item is not in group_list
*/

static Item** find_field_in_group_list(Item *find_item, ORDER *group_list)
{
  const char *db_name;
  const char *table_name;
  const char *field_name;
  ORDER      *found_group= NULL;
  int         found_match_degree= 0;
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  Item_ident *cur_field;
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  int         cur_match_degree= 0;
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  char        name_buff[NAME_LEN+1];
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  if (find_item->type() == Item::FIELD_ITEM ||
      find_item->type() == Item::REF_ITEM)
  {
    db_name=    ((Item_ident*) find_item)->db_name;
    table_name= ((Item_ident*) find_item)->table_name;
    field_name= ((Item_ident*) find_item)->field_name;
  }
  else
    return NULL;

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  if (db_name && lower_case_table_names)
  {
    /* Convert database to lower case for comparison */
    strmake(name_buff, db_name, sizeof(name_buff)-1);
    my_casedn_str(files_charset_info, name_buff);
    db_name= name_buff;
  }

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  DBUG_ASSERT(field_name != 0);
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  for (ORDER *cur_group= group_list ; cur_group ; cur_group= cur_group->next)
  {
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    if ((*(cur_group->item))->real_item()->type() == Item::FIELD_ITEM)
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    {
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      cur_field= (Item_ident*) *cur_group->item;
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      cur_match_degree= 0;
      
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      DBUG_ASSERT(cur_field->field_name != 0);
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      if (!my_strcasecmp(system_charset_info,
                         cur_field->field_name, field_name))
        ++cur_match_degree;
      else
        continue;

      if (cur_field->table_name && table_name)
      {
        /* If field_name is qualified by a table name. */
        if (strcmp(cur_field->table_name, table_name))
          /* Same field names, different tables. */
          return NULL;

        ++cur_match_degree;
        if (cur_field->db_name && db_name)
        {
          /* If field_name is also qualified by a database name. */
          if (strcmp(cur_field->db_name, db_name))
            /* Same field names, different databases. */
            return NULL;
          ++cur_match_degree;
        }
      }

      if (cur_match_degree > found_match_degree)
      {
        found_match_degree= cur_match_degree;
        found_group= cur_group;
      }
      else if (found_group && (cur_match_degree == found_match_degree) &&
               ! (*(found_group->item))->eq(cur_field, 0))
      {
        /*
          If the current resolve candidate matches equally well as the current
          best match, they must reference the same column, otherwise the field
          is ambiguous.
        */
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        my_error(ER_NON_UNIQ_ERROR, MYF(0),
                 find_item->full_name(), current_thd->where);
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        return NULL;
      }
    }
  }

  if (found_group)
    return found_group->item;
  else
    return NULL;
}


/*
  Resolve a column reference in a sub-select.

  SYNOPSIS
    resolve_ref_in_select_and_group()
    thd     current thread
    ref     column reference being resolved
    select  the sub-select that ref is resolved against

  DESCRIPTION
    Resolve a column reference (usually inside a HAVING clause) against the
    SELECT and GROUP BY clauses of the query described by 'select'. The name
    resolution algorithm searches both the SELECT and GROUP BY clauses, and in
    case of a name conflict prefers GROUP BY column names over SELECT names. If
    both clauses contain different fields with the same names, a warning is
    issued that name of 'ref' is ambiguous. We extend ANSI SQL in that when no
    GROUP BY column is found, then a HAVING name is resolved as a possibly
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    derived SELECT column. This extension is allowed only if the
    MODE_ONLY_FULL_GROUP_BY sql mode isn't enabled.
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  NOTES
    The resolution procedure is:
    - Search for a column or derived column named col_ref_i [in table T_j]
      in the SELECT clause of Q.
    - Search for a column named col_ref_i [in table T_j]
      in the GROUP BY clause of Q.
    - If found different columns with the same name in GROUP BY and SELECT
      - issue a warning and return the GROUP BY column,
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      - otherwise
        - if the MODE_ONLY_FULL_GROUP_BY mode is enabled return error
        - else return the found SELECT column.
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  RETURN
    NULL - there was an error, and the error was already reported
    not_found_item - the item was not resolved, no error was reported
    resolved item - if the item was resolved
*/

static Item**
resolve_ref_in_select_and_group(THD *thd, Item_ident *ref, SELECT_LEX *select)
{
  Item **group_by_ref= NULL;
  Item **select_ref= NULL;
  ORDER *group_list= (ORDER*) select->group_list.first;
  bool ambiguous_fields= FALSE;
  uint counter;
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  enum_resolution_type resolution;
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  /*
    Search for a column or derived column named as 'ref' in the SELECT
    clause of the current select.
  */
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  if (!(select_ref= find_item_in_list(ref, *(select->get_item_list()),
                                      &counter, REPORT_EXCEPT_NOT_FOUND,
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                                      &resolution)))
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    return NULL; /* Some error occurred. */
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  if (resolution == RESOLVED_AGAINST_ALIAS)
    ref->alias_name_used= TRUE;
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  /* If this is a non-aggregated field inside HAVING, search in GROUP BY. */
  if (select->having_fix_field && !ref->with_sum_func && group_list)
  {
    group_by_ref= find_field_in_group_list(ref, group_list);
    
    /* Check if the fields found in SELECT and GROUP BY are the same field. */
    if (group_by_ref && (select_ref != not_found_item) &&
        !((*group_by_ref)->eq(*select_ref, 0)))
    {
      ambiguous_fields= TRUE;
      push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN, ER_NON_UNIQ_ERROR,
                          ER(ER_NON_UNIQ_ERROR), ref->full_name(),
                          current_thd->where);

    }
  }

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  if (thd->variables.sql_mode & MODE_ONLY_FULL_GROUP_BY &&
      select_ref != not_found_item && !group_by_ref)
  {
    /*
      Report the error if fields was found only in the SELECT item list and
      the strict mode is enabled.
    */
    my_error(ER_NON_GROUPING_FIELD_USED, MYF(0),
             ref->name, "HAVING");
    return NULL;
  }
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  if (select_ref != not_found_item || group_by_ref)
  {
    if (select_ref != not_found_item && !ambiguous_fields)
    {
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      DBUG_ASSERT(*select_ref != 0);
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      if (!select->ref_pointer_array[counter])
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      {
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        my_error(ER_ILLEGAL_REFERENCE, MYF(0),
                 ref->name, "forward reference in item list");
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        return NULL;
      }
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      DBUG_ASSERT((*select_ref)->fixed);
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      return (select->ref_pointer_array + counter);
    }
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    if (group_by_ref)
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      return group_by_ref;
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    DBUG_ASSERT(FALSE);
    return NULL; /* So there is no compiler warning. */
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  }
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  return (Item**) not_found_item;
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}


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/*
  Resolve the name of an outer select column reference.

  SYNOPSIS
    Item_field::fix_outer_field()
    thd        [in]      current thread
    from_field [in/out]  found field reference or (Field*)not_found_field
    reference  [in/out]  view column if this item was resolved to a view column

  DESCRIPTION
    The method resolves the column reference represented by 'this' as a column
    present in outer selects that contain current select.

  NOTES
    This is the inner loop of Item_field::fix_fields:

      for each outer query Q_k beginning from the inner-most one
      {
        search for a column or derived column named col_ref_i
        [in table T_j] in the FROM clause of Q_k;

        if such a column is not found
          Search for a column or derived column named col_ref_i
          [in table T_j] in the SELECT and GROUP clauses of Q_k.
      }

  IMPLEMENTATION
    In prepared statements, because of cache, find_field_in_tables()
    can resolve fields even if they don't belong to current context.
    In this case this method only finds appropriate context and marks
    current select as dependent. The found reference of field should be
    provided in 'from_field'.

  RETURN
     1 - column succefully resolved and fix_fields() should continue.
     0 - column fully fixed and fix_fields() should return FALSE
    -1 - error occured
*/
int
Item_field::fix_outer_field(THD *thd, Field **from_field, Item **reference)
{
  enum_parsing_place place= NO_MATTER;
  bool field_found= (*from_field != not_found_field);
  bool upward_lookup= FALSE;

  /*
    If there are outer contexts (outer selects, but current select is
    not derived table or view) try to resolve this reference in the
    outer contexts.

    We treat each subselect as a separate namespace, so that different
    subselects may contain columns with the same names. The subselects
    are searched starting from the innermost.
  */
  Name_resolution_context *last_checked_context= context;
  Item **ref= (Item **) not_found_item;
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  SELECT_LEX *current_sel= (SELECT_LEX *) thd->lex->current_select;
  Name_resolution_context *outer_context= 0;
  /* Currently derived tables cannot be correlated */
  if (current_sel->master_unit()->first_select()->linkage !=
      DERIVED_TABLE_TYPE)
    outer_context= context->outer_context;
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  for (;
       outer_context;
       outer_context= outer_context->outer_context)
  {
    SELECT_LEX *select= outer_context->select_lex;
    Item_subselect *prev_subselect_item=
      last_checked_context->select_lex->master_unit()->item;
    last_checked_context= outer_context;
    upward_lookup= TRUE;

    place= prev_subselect_item->parsing_place;
    /*
      If outer_field is set, field was already found by first call
      to find_field_in_tables(). Only need to find appropriate context.
    */
    if (field_found && outer_context->select_lex !=
        cached_table->select_lex)
      continue;
    /*
      In case of a view, find_field_in_tables() writes the pointer to
      the found view field into '*reference', in other words, it
      substitutes this Item_field with the found expression.
    */
    if (field_found || (*from_field= find_field_in_tables(thd, this,
                                          outer_context->
                                            first_name_resolution_table,
                                          outer_context->
                                            last_name_resolution_table,
                                          reference,
                                          IGNORE_EXCEPT_NON_UNIQUE,
                                          TRUE, TRUE)) !=
        not_found_field)
    {
      if (*from_field)
      {
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        if (thd->variables.sql_mode & MODE_ONLY_FULL_GROUP_BY &&
            select->cur_pos_in_select_list != UNDEF_POS)
        {
          /*
            As this is an outer field it should be added to the list of
            non aggregated fields of the outer select.
          */
          marker= select->cur_pos_in_select_list;
          select->non_agg_fields.push_back(this);
        }
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        if (*from_field != view_ref_found)
        {
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          prev_subselect_item->used_tables_cache|= (*from_field)->table->map;
          prev_subselect_item->const_item_cache= 0;
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          if (!last_checked_context->select_lex->having_fix_field &&
              !fixed_as_field)
          {
            Item_outer_ref *rf;
            Query_arena *arena= 0, backup;
            /*
              Each outer field is replaced for an Item_outer_ref object.
              This is done in order to get correct results when the outer
              select employs a temporary table.
              The original fields are saved in the inner_fields_list of the
              outer select. This list is created by the following reasons:
              1. We can't add field items to the outer select list directly
                 because the outer select hasn't been fully fixed yet.
              2. We need a location to refer to in the Item_ref object
                 so the inner_fields_list is used as such temporary
                 reference storage.
              The new Item_outer_ref object replaces the original field and is
              also saved in the inner_refs_list of the outer select. Here
              it is only created. It can be fixed only after the original
              field has been fixed and this is done in the fix_inner_refs()
              function.
            */
            set_field(*from_field);
            arena= thd->activate_stmt_arena_if_needed(&backup);
            rf= new Item_outer_ref(context, this);
            if (!rf)
            {
              if (arena)
                thd->restore_active_arena(arena, &backup);
              return -1;
            }
            *reference= rf;
            select->inner_refs_list.push_back(rf);
            if (arena)
              thd->restore_active_arena(arena, &backup);
            fixed_as_field= 1;
          }
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          if (thd->lex->in_sum_func &&
              thd->lex->in_sum_func->nest_level == 
              thd->lex->current_select->nest_level)
          {
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            Item::Type ref_type= (*reference)->type();
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            set_if_bigger(thd->lex->in_sum_func->max_arg_level,
                          select->nest_level);
            set_field(*from_field);
            fixed= 1;
            mark_as_dependent(thd, last_checked_context->select_lex,
                              context->select_lex, this,
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                              ((ref_type == REF_ITEM ||
                                ref_type == FIELD_ITEM) ?
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                               (Item_ident*) (*reference) : 0));
            return 0;
          }
        }
        else
        {
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          Item::Type ref_type= (*reference)->type();
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          prev_subselect_item->used_tables_cache|=
            (*reference)->used_tables();
          prev_subselect_item->const_item_cache&=
            (*reference)->const_item();
          mark_as_dependent(thd, last_checked_context->select_lex,
                            context->select_lex, this,
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                            ((ref_type == REF_ITEM || ref_type == FIELD_ITEM) ?
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                             (Item_ident*) (*reference) :
                             0));
          /*
            A reference to a view field had been found and we
            substituted it instead of this Item (find_field_in_tables
            does it by assigning the new value to *reference), so now
            we can return from this function.
          */
          return 0;
        }
      }
      break;
    }

    /* Search in SELECT and GROUP lists of the outer select. */
    if (outer_context->resolve_in_select_list)
    {
      if (!(ref= resolve_ref_in_select_and_group(thd, this, select)))
        return -1; /* Some error occurred (e.g. ambiguous names). */
      if (ref != not_found_item)
      {
        DBUG_ASSERT(*ref && (*ref)->fixed);
        prev_subselect_item->used_tables_cache|= (*ref)->used_tables();
        prev_subselect_item->const_item_cache&= (*ref)->const_item();
        break;
      }
    }

    /*
      Reference is not found in this select => this subquery depend on
      outer select (or we just trying to find wrong identifier, in this
      case it does not matter which used tables bits we set)
    */
    prev_subselect_item->used_tables_cache|= OUTER_REF_TABLE_BIT;
    prev_subselect_item->const_item_cache= 0;
  }

  DBUG_ASSERT(ref != 0);
  if (!*from_field)
    return -1;
  if (ref == not_found_item && *from_field == not_found_field)
  {
    if (upward_lookup)
    {
      // We can't say exactly what absent table or field
      my_error(ER_BAD_FIELD_ERROR, MYF(0), full_name(), thd->where);
    }
    else
    {
      /* Call find_field_in_tables only to report the error */
      find_field_in_tables(thd, this,
                           context->first_name_resolution_table,
                           context->last_name_resolution_table,
                           reference, REPORT_ALL_ERRORS,
                           !any_privileges &&
                           TRUE, TRUE);
    }
    return -1;
  }
  else if (ref != not_found_item)
  {
    Item *save;
    Item_ref *rf;

    /* Should have been checked in resolve_ref_in_select_and_group(). */
    DBUG_ASSERT(*ref && (*ref)->fixed);
    /*
      Here, a subset of actions performed by Item_ref::set_properties
      is not enough. So we pass ptr to NULL into Item_[direct]_ref
      constructor, so no initialization is performed, and call 
      fix_fields() below.
    */
    save= *ref;
    *ref= NULL;                             // Don't call set_properties()
    rf= (place == IN_HAVING ?
         new Item_ref(context, ref, (char*) table_name,
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                      (char*) field_name, alias_name_used) :
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         new Item_direct_ref(context, ref, (char*) table_name,
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                             (char*) field_name, alias_name_used));
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    *ref= save;
    if (!rf)
      return -1;
    thd->change_item_tree(reference, rf);
    /*
      rf is Item_ref => never substitute other items (in this case)
      during fix_fields() => we can use rf after fix_fields()
    */
    DBUG_ASSERT(!rf->fixed);                // Assured by Item_ref()
    if (rf->fix_fields(thd, reference) || rf->check_cols(1))
      return -1;

    mark_as_dependent(thd, last_checked_context->select_lex,
                      context->select_lex, this,
                      rf);
    return 0;
  }
  else
  {
    mark_as_dependent(thd, last_checked_context->select_lex,
                      context->select_lex,
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                      this, (Item_ident*)*reference);
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    if (last_checked_context->select_lex->having_fix_field)
    {
      Item_ref *rf;
      rf= new Item_ref(context,
                       (cached_table->db[0] ? cached_table->db : 0),
                       (char*) cached_table->alias, (char*) field_name);
      if (!rf)
        return -1;
      thd->change_item_tree(reference, rf);
      /*
        rf is Item_ref => never substitute other items (in this case)
        during fix_fields() => we can use rf after fix_fields()
      */
      DBUG_ASSERT(!rf->fixed);                // Assured by Item_ref()
      if (rf->fix_fields(thd, reference) || rf->check_cols(1))
        return -1;
      return 0;
    }
  }
  return 1;
}


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/*
  Resolve the name of a column reference.

  SYNOPSIS
    Item_field::fix_fields()
    thd       [in]      current thread
    reference [in/out]  view column if this item was resolved to a view column

  DESCRIPTION
    The method resolves the column reference represented by 'this' as a column
    present in one of: FROM clause, SELECT clause, GROUP BY clause of a query
    Q, or in outer queries that contain Q.

  NOTES
    The name resolution algorithm used is (where [T_j] is an optional table
    name that qualifies the column name):

      resolve_column_reference([T_j].col_ref_i)
      {
        search for a column or derived column named col_ref_i
        [in table T_j] in the FROM clause of Q;

        if such a column is NOT found AND    // Lookup in outer queries.
           there are outer queries
        {
          for each outer query Q_k beginning from the inner-most one
          {
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3755 3756
            search for a column or derived column named col_ref_i
            [in table T_j] in the FROM clause of Q_k;
3757 3758 3759 3760 3761 3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772

            if such a column is not found
              Search for a column or derived column named col_ref_i
              [in table T_j] in the SELECT and GROUP clauses of Q_k.
          }
        }
      }

    Notice that compared to Item_ref::fix_fields, here we first search the FROM
    clause, and then we search the SELECT and GROUP BY clauses.

  RETURN
    TRUE  if error
    FALSE on success
*/

3773
bool Item_field::fix_fields(THD *thd, Item **reference)
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3774
{
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  DBUG_ASSERT(fixed == 0);
3776 3777 3778
  Field *from_field= (Field *)not_found_field;
  bool outer_fixed= false;

3779
  if (!field)					// If field is not checked
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  {
3781 3782 3783 3784 3785
    /*
      In case of view, find_field_in_tables() write pointer to view field
      expression to 'reference', i.e. it substitute that expression instead
      of this Item_field
    */
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3786 3787 3788
    if ((from_field= find_field_in_tables(thd, this,
                                          context->first_name_resolution_table,
                                          context->last_name_resolution_table,
3789 3790
                                          reference,
                                          IGNORE_EXCEPT_NON_UNIQUE,
3791
                                          !any_privileges,
3792
                                          TRUE)) ==
3793
	not_found_field)
3794
    {
3795
      int ret;
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      /* Look up in current select's item_list to find aliased fields */
      if (thd->lex->current_select->is_item_list_lookup)
      {
        uint counter;
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        enum_resolution_type resolution;
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        Item** res= find_item_in_list(this, thd->lex->current_select->item_list,
                                      &counter, REPORT_EXCEPT_NOT_FOUND,
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3803
                                      &resolution);
3804 3805
        if (!res)
          return 1;
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        if (resolution == RESOLVED_AGAINST_ALIAS)
          alias_name_used= TRUE;
3808
        if (res != (Item **)not_found_item)
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        {
3810 3811 3812 3813 3814 3815 3816 3817
          if ((*res)->type() == Item::FIELD_ITEM)
          {
            /*
             It's an Item_field referencing another Item_field in the select
             list.
             use the field from the Item_field in the select list and leave
             the Item_field instance in place.
            */
3818 3819 3820

            Field *field= (*((Item_field**)res))->field;

3821 3822 3823 3824 3825 3826 3827 3828 3829
            if (field == NULL)
            {
              /* The column to which we link isn't valid. */
              my_error(ER_BAD_FIELD_ERROR, MYF(0), (*res)->name, 
                       current_thd->where);
              return(1);
            }

            set_field(field);
3830 3831 3832 3833 3834 3835 3836 3837 3838
            return 0;
          }
          else
          {
            /*
              It's not an Item_field in the select list so we must make a new
              Item_ref to point to the Item in the select list and replace the
              Item_field created by the parser with the new Item_ref.
            */
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            Item_ref *rf= new Item_ref(context, db_name,table_name,field_name);
3840 3841
            if (!rf)
              return 1;
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            thd->change_item_tree(reference, rf);
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            /*
              Because Item_ref never substitutes itself with other items 
              in Item_ref::fix_fields(), we can safely use the original 
              pointer to it even after fix_fields()
             */
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            return rf->fix_fields(thd, reference) ||  rf->check_cols(1);
3849
          }
3850 3851
        }
      }
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      if ((ret= fix_outer_field(thd, &from_field, reference)) < 0)
        goto error;
      else if (!ret)
        return FALSE;
      outer_fixed= TRUE;
3857
    }
3858
    else if (!from_field)
3859
      goto error;
3860

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VIEW  
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3861 3862 3863 3864
    /*
      if it is not expression from merged VIEW we will set this field.

      We can leave expression substituted from view for next PS/SP rexecution
3865
      (i.e. do not register this substitution for reverting on cleanup()
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VIEW  
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3866
      (register_item_tree_changing())), because this subtree will be
3867
      fix_field'ed during setup_tables()->setup_underlying() (i.e. before
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VIEW  
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3868 3869 3870 3871 3872
      all other expressions of query, and references on tables which do
      not present in query will not make problems.

      Also we suppose that view can't be changed during PS/SP life.
    */
3873 3874 3875
    if (from_field == view_ref_found)
      return FALSE;

3876
    if (!outer_fixed && cached_table && cached_table->select_lex &&
3877 3878
        context->select_lex &&
        cached_table->select_lex != context->select_lex)
3879 3880 3881 3882
    {
      int ret;
      if ((ret= fix_outer_field(thd, &from_field, reference)) < 0)
        goto error;
3883
      if (!ret)
3884
        return FALSE;
3885
      outer_fixed= 1;
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    }

3888
    set_field(from_field);
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    if (thd->lex->in_sum_func &&
        thd->lex->in_sum_func->nest_level == 
        thd->lex->current_select->nest_level)
      set_if_bigger(thd->lex->in_sum_func->max_arg_level,
                    thd->lex->current_select->nest_level);
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3894
  }
3895
  else if (thd->mark_used_columns != MARK_COLUMNS_NONE)
3896
  {
3897
    TABLE *table= field->table;
3898 3899
    MY_BITMAP *current_bitmap, *other_bitmap;
    if (thd->mark_used_columns == MARK_COLUMNS_READ)
3900
    {
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      current_bitmap= table->read_set;
      other_bitmap=   table->write_set;
    }
    else
    {
      current_bitmap= table->write_set;
      other_bitmap=   table->read_set;
    }
    if (!bitmap_fast_test_and_set(current_bitmap, field->field_index))
    {
      if (!bitmap_is_set(other_bitmap, field->field_index))
      {
        /* First usage of column */
        table->used_fields++;                     // Used to optimize loops
3915
        /* purecov: begin inspected */
3916
        table->covering_keys.intersect(field->part_of_key);
3917
        /* purecov: end */
3918
      }
3919
    }
3920
  }
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VIEW  
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3921 3922 3923 3924 3925 3926 3927 3928 3929 3930 3931 3932
#ifndef NO_EMBEDDED_ACCESS_CHECKS
  if (any_privileges)
  {
    char *db, *tab;
    if (cached_table->view)
    {
      db= cached_table->view_db.str;
      tab= cached_table->view_name.str;
    }
    else
    {
      db= cached_table->db;
3933
      tab= cached_table->table_name;
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VIEW  
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3934 3935 3936 3937 3938
    }
    if (!(have_privileges= (get_column_grant(thd, &field->table->grant,
                                             db, tab, field_name) &
                            VIEW_ANY_ACL)))
    {
3939
      my_error(ER_COLUMNACCESS_DENIED_ERROR, MYF(0),
3940 3941
               "ANY", thd->security_ctx->priv_user,
               thd->security_ctx->host_or_ip, field_name, tab);
3942
      goto error;
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VIEW  
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3943 3944 3945
    }
  }
#endif
3946
  fixed= 1;
3947 3948 3949 3950 3951 3952 3953
  if (thd->variables.sql_mode & MODE_ONLY_FULL_GROUP_BY &&
      !outer_fixed && !thd->lex->in_sum_func &&
      thd->lex->current_select->cur_pos_in_select_list != UNDEF_POS)
  {
    thd->lex->current_select->non_agg_fields.push_back(this);
    marker= thd->lex->current_select->cur_pos_in_select_list;
  }
3954
  return FALSE;
3955 3956 3957 3958

error:
  context->process_error(thd);
  return TRUE;
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3959 3960
}

3961 3962 3963 3964 3965 3966 3967 3968

Item *Item_field::safe_charset_converter(CHARSET_INFO *tocs)
{
  no_const_subst= 1;
  return Item::safe_charset_converter(tocs);
}


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void Item_field::cleanup()
{
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  DBUG_ENTER("Item_field::cleanup");
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  Item_ident::cleanup();
3973 3974
  /*
    Even if this object was created by direct link to field in setup_wild()
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3975
    it will be linked correctly next time by name of field and table alias.
3976 3977
    I.e. we can drop 'field'.
   */
3978
  field= result_field= 0;
3979
  null_value= FALSE;
3980
  DBUG_VOID_RETURN;
3981
}
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3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994 3995 3996 3997 3998 3999 4000 4001 4002

/*
  Find a field among specified multiple equalities 

  SYNOPSIS
    find_item_equal()
    cond_equal   reference to list of multiple equalities where
                 the field (this object) is to be looked for
  
  DESCRIPTION
    The function first searches the field among multiple equalities
    of the current level (in the cond_equal->current_level list).
    If it fails, it continues searching in upper levels accessed
    through a pointer cond_equal->upper_levels.
    The search terminates as soon as a multiple equality containing 
    the field is found. 

  RETURN VALUES
    First Item_equal containing the field, if success
    0, otherwise
*/
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4003 4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021 4022 4023
Item_equal *Item_field::find_item_equal(COND_EQUAL *cond_equal)
{
  Item_equal *item= 0;
  while (cond_equal)
  {
    List_iterator_fast<Item_equal> li(cond_equal->current_level);
    while ((item= li++))
    {
      if (item->contains(field))
        return item;
    }
    /* 
      The field is not found in any of the multiple equalities
      of the current level. Look for it in upper levels
    */
    cond_equal= cond_equal->upper_levels;
  }
  return 0;
}


4024 4025 4026 4027 4028 4029 4030 4031 4032 4033 4034 4035 4036 4037 4038 4039 4040 4041 4042 4043 4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054 4055 4056 4057 4058
/*
  Check whether a field can be substituted by an equal item

  SYNOPSIS
    equal_fields_propagator()
      arg - *arg != NULL <-> the field is in the context where
            substitution for an equal item is valid
   
  DESCRIPTION
    The function checks whether a substitution of the field
    occurrence for an equal item is valid.

  NOTES
    The following statement is not always true:
    x=y => F(x)=F(x/y).
    This means substitution of an item for an equal item not always
    yields an equavalent condition.
    Here's an example:
      'a'='a '
      (LENGTH('a')=1) != (LENGTH('a ')=2)
    Such a substitution is surely valid if either the substituted
    field is not of a STRING type or if it is an argument of
    a comparison  predicate.  

  RETURN
    TRUE   substitution is valid
    FALSE  otherwise
*/

bool Item_field::subst_argument_checker(byte **arg)
{
  return (result_type() != STRING_RESULT) || (*arg);
}


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/*
4060 4061
  Set a pointer to the multiple equality the field reference belongs to
  (if any)
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  SYNOPSIS
    equal_fields_propagator()
4065 4066
      arg - reference to list of multiple equalities where
            the field (this object) is to be looked for
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4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077
  
  DESCRIPTION
    The function looks for a multiple equality containing the field item
    among those referenced by arg.
    In the case such equality exists the function does the following.
    If the found multiple equality contains a constant, then the field
    reference is substituted for this constant, otherwise it sets a pointer
    to the multiple equality in the field item.

  NOTES
    This function is supposed to be called as a callback parameter in calls
4078
    of the compile method.  
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4079 4080 4081 4082 4083

  RETURN VALUES
    pointer to the replacing constant item, if the field item was substituted 
    pointer to the field item, otherwise.
*/
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4084

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Item *Item_field::equal_fields_propagator(byte *arg)
{
  if (no_const_subst)
    return this;
  item_equal= find_item_equal((COND_EQUAL *) arg);
  Item *item= 0;
  if (item_equal)
    item= item_equal->get_const();
4093 4094 4095 4096 4097 4098 4099 4100 4101 4102 4103
  /*
    Disable const propagation for items used in different comparison contexts.
    This must be done because, for example, Item_hex_string->val_int() is not
    the same as (Item_hex_string->val_str() in BINARY column)->val_int().
    We cannot simply disable the replacement in a particular context (
    e.g. <bin_col> = <int_col> AND <bin_col> = <hex_string>) since
    Items don't know the context they are in and there are functions like 
    IF (<hex_string>, 'yes', 'no').
    The same problem occurs when comparing a DATE/TIME field with a
    DATE/TIME represented as an int and as a string.
  */
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4104 4105
  if (!item ||
      (cmp_context != (Item_result)-1 && item->cmp_context != cmp_context))
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    item= this;
  return item;
}


/*
4112 4113 4114 4115
  Mark the item to not be part of substitution if it's not a binary item
  See comments in Arg_comparator::set_compare_func() for details
*/

4116
bool Item_field::set_no_const_sub(byte *arg)
4117 4118 4119
{
  if (field->charset() != &my_charset_bin)
    no_const_subst=1;
4120
  return FALSE;
4121 4122 4123 4124
}


/*
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4125
  Replace an Item_field for an equal Item_field that evaluated earlier
4126
  (if any)
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4127 4128
   
  SYNOPSIS
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4129
    replace_equal_field_()
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4130 4131 4132
    arg - a dummy parameter, is not used here
  
  DESCRIPTION
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4133 4134
    The function returns a pointer to an item that is taken from
    the very beginning of the item_equal list which the Item_field
4135 4136 4137
    object refers to (belongs to) unless item_equal contains  a constant
    item. In this case the function returns this constant item, 
    (if the substitution does not require conversion).   
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4138 4139
    If the Item_field object does not refer any Item_equal object
    'this' is returned 
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4140 4141 4142

  NOTES
    This function is supposed to be called as a callback parameter in calls
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4143
    of the thransformer method.  
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4144 4145

  RETURN VALUES
4146 4147
    pointer to a replacement Item_field if there is a better equal item or
    a pointer to a constant equal item;
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4148
    this - otherwise.
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*/

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Item *Item_field::replace_equal_field(byte *arg)
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4152 4153 4154
{
  if (item_equal)
  {
4155 4156 4157 4158 4159 4160 4161 4162
    Item *const_item= item_equal->get_const();
    if (const_item)
    {
      if (cmp_context != (Item_result)-1 &&
          const_item->cmp_context != cmp_context)
        return this;
      return const_item;
    }
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4163
    Item_field *subst= item_equal->get_first();
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4164
    if (subst && !field->eq(subst->field))
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4165
      return subst;
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4166
  }
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4167
  return this;
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4168
}
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4169

4170

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4171
void Item::init_make_field(Send_field *tmp_field,
4172
			   enum enum_field_types field_type_arg)
4173
{
4174
  char *empty_name= (char*) "";
4175
  tmp_field->db_name=		empty_name;
4176 4177 4178 4179
  tmp_field->org_table_name=	empty_name;
  tmp_field->org_col_name=	empty_name;
  tmp_field->table_name=	empty_name;
  tmp_field->col_name=		name;
4180
  tmp_field->charsetnr=         collation.collation->number;
4181 4182 4183
  tmp_field->flags=             (maybe_null ? 0 : NOT_NULL_FLAG) | 
                                (my_binary_compare(collation.collation) ?
                                 BINARY_FLAG : 0);
4184
  tmp_field->type=              field_type_arg;
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4185 4186
  tmp_field->length=max_length;
  tmp_field->decimals=decimals;
4187 4188
  if (unsigned_flag)
    tmp_field->flags |= UNSIGNED_FLAG;
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4189 4190
}

4191
void Item::make_field(Send_field *tmp_field)
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4192
{
4193
  init_make_field(tmp_field, field_type());
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4194 4195 4196
}


4197
enum_field_types Item::string_field_type() const
4198
{
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4199
  enum_field_types f_type= MYSQL_TYPE_VAR_STRING;
4200
  if (max_length >= 16777216)
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    f_type= MYSQL_TYPE_LONG_BLOB;
4202
  else if (max_length >= 65536)
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    f_type= MYSQL_TYPE_MEDIUM_BLOB;
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  return f_type;
4205 4206 4207 4208 4209 4210
}


void Item_empty_string::make_field(Send_field *tmp_field)
{
  init_make_field(tmp_field, string_field_type());
4211 4212
}

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4214
enum_field_types Item::field_type() const
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{
4216
  switch (result_type()) {
4217
  case STRING_RESULT:  return string_field_type();
4218 4219 4220
  case INT_RESULT:     return MYSQL_TYPE_LONGLONG;
  case DECIMAL_RESULT: return MYSQL_TYPE_NEWDECIMAL;
  case REAL_RESULT:    return MYSQL_TYPE_DOUBLE;
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4221 4222 4223
  case ROW_RESULT:
  default:
    DBUG_ASSERT(0);
4224 4225
    return MYSQL_TYPE_VARCHAR;
  }
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}

4228

4229 4230 4231 4232 4233 4234 4235 4236 4237 4238 4239 4240 4241 4242 4243 4244
/*
  Create a field to hold a string value from an item

  SYNOPSIS
    make_string_field()
    table		Table for which the field is created

  IMPLEMENTATION
    If max_length > CONVERT_IF_BIGGER_TO_BLOB create a blob
    If max_length > 0 create a varchar
    If max_length == 0 create a CHAR(0) 
*/


Field *Item::make_string_field(TABLE *table)
{
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4245
  Field *field;
4246 4247
  DBUG_ASSERT(collation.collation);
  if (max_length/collation.collation->mbmaxlen > CONVERT_IF_BIGGER_TO_BLOB)
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    field= new Field_blob(max_length, maybe_null, name,
4249
                          collation.collation);
4250
  /* Item_type_holder holds the exact type, do not change it */
4251
  else if (max_length > 0 &&
4252
      (type() != Item::TYPE_HOLDER || field_type() != MYSQL_TYPE_STRING))
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4253
    field= new Field_varstring(max_length, maybe_null, name, table->s,
4254
                               collation.collation);
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4255 4256 4257 4258 4259 4260
  else
    field= new Field_string(max_length, maybe_null, name,
                            collation.collation);
  if (field)
    field->init(table);
  return field;
4261 4262 4263
}


4264 4265 4266 4267
/*
  Create a field based on field_type of argument

  For now, this is only used to create a field for
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  IFNULL(x,something) and time functions
4269 4270 4271 4272 4273 4274

  RETURN
    0  error
    #  Created field
*/

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Field *Item::tmp_table_field_from_field_type(TABLE *table, bool fixed_length)
4276
{
4277 4278 4279 4280
  /*
    The field functions defines a field to be not null if null_ptr is not 0
  */
  uchar *null_ptr= maybe_null ? (uchar*) "" : 0;
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4281
  Field *field;
4282 4283

  switch (field_type()) {
4284
  case MYSQL_TYPE_DECIMAL:
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  case MYSQL_TYPE_NEWDECIMAL:
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    field= new Field_new_decimal((char*) 0, max_length, null_ptr, 0,
                                 Field::NONE, name, decimals, 0,
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                                 unsigned_flag);
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4289
    break;
4290
  case MYSQL_TYPE_TINY:
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    field= new Field_tiny((char*) 0, max_length, null_ptr, 0, Field::NONE,
			  name, 0, unsigned_flag);
    break;
4294
  case MYSQL_TYPE_SHORT:
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    field= new Field_short((char*) 0, max_length, null_ptr, 0, Field::NONE,
			   name, 0, unsigned_flag);
    break;
4298
  case MYSQL_TYPE_LONG:
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    field= new Field_long((char*) 0, max_length, null_ptr, 0, Field::NONE,
			  name, 0, unsigned_flag);
    break;
4302 4303
#ifdef HAVE_LONG_LONG
  case MYSQL_TYPE_LONGLONG:
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    field= new Field_longlong((char*) 0, max_length, null_ptr, 0, Field::NONE,
			      name, 0, unsigned_flag);
    break;
4307
#endif
4308
  case MYSQL_TYPE_FLOAT:
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    field= new Field_float((char*) 0, max_length, null_ptr, 0, Field::NONE,
			   name, decimals, 0, unsigned_flag);
    break;
4312
  case MYSQL_TYPE_DOUBLE:
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    field= new Field_double((char*) 0, max_length, null_ptr, 0, Field::NONE,
			    name, decimals, 0, unsigned_flag);
    break;
4316
  case MYSQL_TYPE_NULL:
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    field= new Field_null((char*) 0, max_length, Field::NONE,
			  name, &my_charset_bin);
    break;
4320
  case MYSQL_TYPE_INT24:
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    field= new Field_medium((char*) 0, max_length, null_ptr, 0, Field::NONE,
			    name, 0, unsigned_flag);
    break;
4324
  case MYSQL_TYPE_NEWDATE:
4325
  case MYSQL_TYPE_DATE:
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    field= new Field_date(maybe_null, name, &my_charset_bin);
    break;
4328
  case MYSQL_TYPE_TIME:
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    field= new Field_time(maybe_null, name, &my_charset_bin);
    break;
4331
  case MYSQL_TYPE_TIMESTAMP:
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    field= new Field_timestamp(maybe_null, name, &my_charset_bin);
    break;
4334
  case MYSQL_TYPE_DATETIME:
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    field= new Field_datetime(maybe_null, name, &my_charset_bin);
    break;
4337
  case MYSQL_TYPE_YEAR:
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    field= new Field_year((char*) 0, max_length, null_ptr, 0, Field::NONE,
			  name);
    break;
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  case MYSQL_TYPE_BIT:
4342
    field= new Field_bit_as_char(NULL, max_length, null_ptr, 0,
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                                 Field::NONE, name);
    break;
4345
  default:
4346
    /* This case should never be chosen */
4347 4348
    DBUG_ASSERT(0);
    /* If something goes awfully wrong, it's better to get a string than die */
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  case MYSQL_TYPE_STRING:
    if (fixed_length && max_length < CONVERT_IF_BIGGER_TO_BLOB)
    {
      field= new Field_string(max_length, maybe_null, name,
                              collation.collation);
      break;
    }
    /* Fall through to make_string_field() */
4357 4358
  case MYSQL_TYPE_ENUM:
  case MYSQL_TYPE_SET:
4359
  case MYSQL_TYPE_VAR_STRING:
4360
  case MYSQL_TYPE_VARCHAR:
4361
    return make_string_field(table);
4362 4363 4364 4365
  case MYSQL_TYPE_TINY_BLOB:
  case MYSQL_TYPE_MEDIUM_BLOB:
  case MYSQL_TYPE_LONG_BLOB:
  case MYSQL_TYPE_BLOB:
4366
    if (this->type() == Item::TYPE_HOLDER)
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      field= new Field_blob(max_length, maybe_null, name, collation.collation,
                            1);
4369
    else
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      field= new Field_blob(max_length, maybe_null, name, collation.collation);
4371
    break;					// Blob handled outside of case
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  case MYSQL_TYPE_GEOMETRY:
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    return new Field_geom(max_length, maybe_null, name, table->s,
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                          (Field::geometry_type)
                          ((Item_geometry_func *)this)->get_geometry_type());
4376
  }
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  if (field)
    field->init(table);
  return field;
4380 4381
}

4382

4383 4384
/* ARGSUSED */
void Item_field::make_field(Send_field *tmp_field)
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4385
{
4386
  field->make_field(tmp_field);
4387
  DBUG_ASSERT(tmp_field->table_name != 0);
4388 4389
  if (name)
    tmp_field->col_name=name;			// Use user supplied name
4390 4391 4392 4393
  if (table_name)
    tmp_field->table_name= table_name;
  if (db_name)
    tmp_field->db_name= db_name;
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}

4396

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/*
4398
  Set a field:s value from a item
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*/

void Item_field::save_org_in_field(Field *to)
{
  if (field->is_null())
  {
    null_value=1;
4406
    set_field_to_null_with_conversions(to, 1);
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  }
  else
  {
    to->set_notnull();
    field_conv(to,field);
    null_value=0;
  }
}

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int Item_field::save_in_field(Field *to, bool no_conversions)
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{
4418
  int res;
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  if (result_field->is_null())
  {
    null_value=1;
4422
    res= set_field_to_null_with_conversions(to, no_conversions);
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  }
  else
  {
    to->set_notnull();
4427
    res= field_conv(to,result_field);
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    null_value=0;
  }
4430
  return res;
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}

4433

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/*
  Store null in field

  SYNOPSIS
    save_in_field()
    field		Field where we want to store NULL

  DESCRIPTION
    This is used on INSERT.
    Allow NULL to be inserted in timestamp and auto_increment values

  RETURN VALUES
    0	 ok
    1	 Field doesn't support NULL values and can't handle 'field = NULL'
*/   

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int Item_null::save_in_field(Field *field, bool no_conversions)
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{
4452
  return set_field_to_null_with_conversions(field, no_conversions);
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}


4456 4457 4458 4459 4460 4461 4462 4463
/*
  Store null in field

  SYNOPSIS
    save_safe_in_field()
    field		Field where we want to store NULL

  RETURN VALUES
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    0	 OK
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    1	 Field doesn't support NULL values
*/   

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int Item_null::save_safe_in_field(Field *field)
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{
  return set_field_to_null(field);
}


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int Item::save_in_field(Field *field, bool no_conversions)
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{
4476
  int error;
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  if (result_type() == STRING_RESULT ||
      result_type() == REAL_RESULT &&
      field->result_type() == STRING_RESULT)
  {
    String *result;
4482
    CHARSET_INFO *cs= collation.collation;
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    char buff[MAX_FIELD_WIDTH];		// Alloc buffer for small columns
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    str_value.set_quick(buff, sizeof(buff), cs);
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    result=val_str(&str_value);
    if (null_value)
4487
    {
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      str_value.set_quick(0, 0, cs);
4489
      return set_field_to_null_with_conversions(field, no_conversions);
4490
    }
4491 4492 4493

    /* NOTE: If null_value == FALSE, "result" must be not NULL.  */

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    field->set_notnull();
4495
    error=field->store(result->ptr(),result->length(),cs);
4496
    str_value.set_quick(0, 0, cs);
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  }
  else if (result_type() == REAL_RESULT)
  {
4500
    double nr= val_real();
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    if (null_value)
      return set_field_to_null(field);
    field->set_notnull();
4504
    error=field->store(nr);
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  }
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  else if (result_type() == DECIMAL_RESULT)
  {
    my_decimal decimal_value;
    my_decimal *value= val_decimal(&decimal_value);
    if (null_value)
      return set_field_to_null(field);
    field->set_notnull();
    error=field->store_decimal(value);
  }
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  else
  {
    longlong nr=val_int();
    if (null_value)
4519
      return set_field_to_null_with_conversions(field, no_conversions);
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    field->set_notnull();
4521
    error=field->store(nr, unsigned_flag);
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  }
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  return error;
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}

4526

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int Item_string::save_in_field(Field *field, bool no_conversions)
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{
  String *result;
  result=val_str(&str_value);
  if (null_value)
    return set_field_to_null(field);
  field->set_notnull();
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  return field->store(result->ptr(),result->length(),collation.collation);
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}

4537

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int Item_uint::save_in_field(Field *field, bool no_conversions)
4539
{
4540
  /* Item_int::save_in_field handles both signed and unsigned. */
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  return Item_int::save_in_field(field, no_conversions);
4542 4543
}

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int Item_int::save_in_field(Field *field, bool no_conversions)
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{
  longlong nr=val_int();
  if (null_value)
    return set_field_to_null(field);
  field->set_notnull();
4551
  return field->store(nr, unsigned_flag);
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}

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int Item_decimal::save_in_field(Field *field, bool no_conversions)
{
  field->set_notnull();
  return field->store_decimal(&decimal_value);
}


4562 4563 4564 4565 4566 4567 4568 4569 4570 4571 4572 4573 4574 4575 4576 4577
bool Item_int::eq(const Item *arg, bool binary_cmp) const
{
  /* No need to check for null value as basic constant can't be NULL */
  if (arg->basic_const_item() && arg->type() == type())
  {
    /*
      We need to cast off const to call val_int(). This should be OK for
      a basic constant.
    */
    Item *item= (Item*) arg;
    return item->val_int() == value && item->unsigned_flag == unsigned_flag;
  }
  return FALSE;
}


4578
Item *Item_int_with_ref::clone_item()
4579
{
4580
  DBUG_ASSERT(ref->const_item());
4581 4582 4583 4584 4585 4586 4587 4588 4589 4590
  /*
    We need to evaluate the constant to make sure it works with
    parameter markers.
  */
  return (ref->unsigned_flag ?
          new Item_uint(ref->name, ref->val_int(), ref->max_length) :
          new Item_int(ref->name, ref->val_int(), ref->max_length));
}


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Item_num *Item_uint::neg()
{
4593
  Item_decimal *item= new Item_decimal(value, 1);
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  return item->neg();
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}
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4598 4599 4600 4601 4602 4603 4604 4605 4606 4607 4608 4609 4610 4611 4612 4613 4614 4615 4616 4617 4618 4619 4620
static uint nr_of_decimals(const char *str, const char *end)
{
  const char *decimal_point;

  /* Find position for '.' */
  for (;;)
  {
    if (str == end)
      return 0;
    if (*str == 'e' || *str == 'E')
      return NOT_FIXED_DEC;    
    if (*str++ == '.')
      break;
  }
  decimal_point= str;
  for (; my_isdigit(system_charset_info, *str) ; str++)
    ;
  if (*str == 'e' || *str == 'E')
    return NOT_FIXED_DEC;
  return (uint) (str - decimal_point);
}


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/*
  This function is only called during parsing. We will signal an error if
  value is not a true double value (overflow)
*/

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Item_float::Item_float(const char *str_arg, uint length)
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{
  int error;
4629 4630 4631
  char *end_not_used;
  value= my_strntod(&my_charset_bin, (char*) str_arg, length, &end_not_used,
                    &error);
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  if (error)
  {
    /*
      Note that we depend on that str_arg is null terminated, which is true
      when we are in the parser
    */
    DBUG_ASSERT(str_arg[length] == 0);
4639
    my_error(ER_ILLEGAL_VALUE_FOR_TYPE, MYF(0), "double", (char*) str_arg);
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  }
  presentation= name=(char*) str_arg;
4642
  decimals=(uint8) nr_of_decimals(str_arg, str_arg+length);
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  max_length=length;
  fixed= 1;
}


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int Item_float::save_in_field(Field *field, bool no_conversions)
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4649
{
4650
  double nr= val_real();
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  if (null_value)
    return set_field_to_null(field);
  field->set_notnull();
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  return field->store(nr);
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}

4657

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4658
void Item_float::print(String *str)
4659 4660 4661 4662 4663 4664 4665 4666
{
  if (presentation)
  {
    str->append(presentation);
    return;
  }
  char buffer[20];
  String num(buffer, sizeof(buffer), &my_charset_bin);
4667
  num.set_real(value, decimals, &my_charset_bin);
4668 4669 4670 4671
  str->append(num);
}


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/*
  hex item
  In string context this is a binary string.
  In number context this is a longlong value.
*/
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4678
bool Item_float::eq(const Item *arg, bool binary_cmp) const
4679 4680 4681 4682 4683 4684 4685 4686
{
  if (arg->basic_const_item() && arg->type() == type())
  {
    /*
      We need to cast off const to call val_int(). This should be OK for
      a basic constant.
    */
    Item *item= (Item*) arg;
4687
    return item->val_real() == value;
4688 4689 4690 4691
  }
  return FALSE;
}

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inline uint char_val(char X)
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{
  return (uint) (X >= '0' && X <= '9' ? X-'0' :
		 X >= 'A' && X <= 'Z' ? X-'A'+10 :
		 X-'a'+10);
}

4700

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4701
Item_hex_string::Item_hex_string(const char *str, uint str_length)
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{
  name=(char*) str-2;				// Lex makes this start with 0x
  max_length=(str_length+1)/2;
  char *ptr=(char*) sql_alloc(max_length+1);
  if (!ptr)
    return;
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  str_value.set(ptr,max_length,&my_charset_bin);
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  char *end=ptr+max_length;
  if (max_length*2 != str_length)
    *ptr++=char_val(*str++);			// Not even, assume 0 prefix
  while (ptr != end)
  {
    *ptr++= (char) (char_val(str[0])*16+char_val(str[1]));
    str+=2;
  }
  *ptr=0;					// Keep purify happy
4718
  collation.set(&my_charset_bin, DERIVATION_COERCIBLE);
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  fixed= 1;
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  unsigned_flag= 1;
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}

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longlong Item_hex_string::val_int()
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{
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  // following assert is redundant, because fixed=1 assigned in constructor
4726
  DBUG_ASSERT(fixed == 1);
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  char *end=(char*) str_value.ptr()+str_value.length(),
       *ptr=end-min(str_value.length(),sizeof(longlong));

  ulonglong value=0;
  for (; ptr != end ; ptr++)
    value=(value << 8)+ (ulonglong) (uchar) *ptr;
  return (longlong) value;
}


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my_decimal *Item_hex_string::val_decimal(my_decimal *decimal_value)
{
  // following assert is redundant, because fixed=1 assigned in constructor
  DBUG_ASSERT(fixed == 1);
  ulonglong value= (ulonglong)val_int();
  int2my_decimal(E_DEC_FATAL_ERROR, value, TRUE, decimal_value);
  return (decimal_value);
}


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int Item_hex_string::save_in_field(Field *field, bool no_conversions)
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{
  field->set_notnull();
  if (field->result_type() == STRING_RESULT)
4751 4752 4753 4754 4755 4756
    return field->store(str_value.ptr(), str_value.length(), 
                        collation.collation);

  ulonglong nr;
  uint32 length= str_value.length();
  if (length > 8)
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  {
4758 4759
    nr= field->flags & UNSIGNED_FLAG ? ULONGLONG_MAX : LONGLONG_MAX;
    goto warn;
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  }
4761 4762
  nr= (ulonglong) val_int();
  if ((length == 8) && !(field->flags & UNSIGNED_FLAG) && (nr > LONGLONG_MAX))
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  {
4764 4765
    nr= LONGLONG_MAX;
    goto warn;
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  }
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  return field->store((longlong) nr, TRUE);  // Assume hex numbers are unsigned
4768 4769

warn:
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  if (!field->store((longlong) nr, TRUE))
4771 4772 4773
    field->set_warning(MYSQL_ERROR::WARN_LEVEL_WARN, ER_WARN_DATA_OUT_OF_RANGE,
                       1);
  return 1;
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}


4777
bool Item_hex_string::eq(const Item *arg, bool binary_cmp) const
4778 4779 4780 4781 4782 4783 4784 4785 4786 4787
{
  if (arg->basic_const_item() && arg->type() == type())
  {
    if (binary_cmp)
      return !stringcmp(&str_value, &arg->str_value);
    return !sortcmp(&str_value, &arg->str_value, collation.collation);
  }
  return FALSE;
}

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Item *Item_hex_string::safe_charset_converter(CHARSET_INFO *tocs)
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{
  Item_string *conv;
  String tmp, *str= val_str(&tmp);

  if (!(conv= new Item_string(str->ptr(), str->length(), tocs)))
    return NULL;
  conv->str_value.copy();
4797
  conv->str_value.mark_as_const();
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  return conv;
}


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/*
  bin item.
  In string context this is a binary string.
  In number context this is a longlong value.
*/
  
Item_bin_string::Item_bin_string(const char *str, uint str_length)
{
  const char *end= str + str_length - 1;
  uchar bits= 0;
  uint power= 1;

  name= (char*) str - 2;
  max_length= (str_length + 7) >> 3;
  char *ptr= (char*) sql_alloc(max_length + 1);
  if (!ptr)
    return;
  str_value.set(ptr, max_length, &my_charset_bin);
  ptr+= max_length - 1;
  ptr[1]= 0;                     // Set end null for string
  for (; end >= str; end--)
  {
    if (power == 256)
    {
      power= 1;
      *ptr--= bits;
      bits= 0;     
    }
    if (*end == '1')
      bits|= power; 
    power<<= 1;
  }
  *ptr= (char) bits;
  collation.set(&my_charset_bin, DERIVATION_COERCIBLE);
  fixed= 1;
}


4840 4841 4842 4843 4844
/*
  Pack data in buffer for sending
*/

bool Item_null::send(Protocol *protocol, String *packet)
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{
4846
  return protocol->store_null();
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}

/*
4850
  This is only called from items that is not of type item_field
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*/

4853
bool Item::send(Protocol *protocol, String *buffer)
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{
4855
  bool result;
4856
  enum_field_types f_type;
4857
  LINT_INIT(result);                     // Will be set if null_value == 0
4858

4859
  switch ((f_type=field_type())) {
4860
  default:
4861 4862 4863 4864 4865 4866 4867 4868 4869
  case MYSQL_TYPE_NULL:
  case MYSQL_TYPE_DECIMAL:
  case MYSQL_TYPE_ENUM:
  case MYSQL_TYPE_SET:
  case MYSQL_TYPE_TINY_BLOB:
  case MYSQL_TYPE_MEDIUM_BLOB:
  case MYSQL_TYPE_LONG_BLOB:
  case MYSQL_TYPE_BLOB:
  case MYSQL_TYPE_GEOMETRY:
4870 4871
  case MYSQL_TYPE_STRING:
  case MYSQL_TYPE_VAR_STRING:
4872
  case MYSQL_TYPE_VARCHAR:
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  case MYSQL_TYPE_BIT:
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  case MYSQL_TYPE_NEWDECIMAL:
4875 4876 4877
  {
    String *res;
    if ((res=val_str(buffer)))
4878
      result= protocol->store(res->ptr(),res->length(),res->charset());
4879 4880 4881 4882 4883 4884 4885 4886 4887 4888 4889
    break;
  }
  case MYSQL_TYPE_TINY:
  {
    longlong nr;
    nr= val_int();
    if (!null_value)
      result= protocol->store_tiny(nr);
    break;
  }
  case MYSQL_TYPE_SHORT:
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4890
  case MYSQL_TYPE_YEAR:
4891 4892 4893 4894 4895 4896 4897
  {
    longlong nr;
    nr= val_int();
    if (!null_value)
      result= protocol->store_short(nr);
    break;
  }
4898
  case MYSQL_TYPE_INT24:
4899 4900 4901 4902 4903 4904 4905 4906 4907 4908 4909 4910 4911 4912 4913 4914
  case MYSQL_TYPE_LONG:
  {
    longlong nr;
    nr= val_int();
    if (!null_value)
      result= protocol->store_long(nr);
    break;
  }
  case MYSQL_TYPE_LONGLONG:
  {
    longlong nr;
    nr= val_int();
    if (!null_value)
      result= protocol->store_longlong(nr, unsigned_flag);
    break;
  }
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  case MYSQL_TYPE_FLOAT:
  {
    float nr;
4918
    nr= (float) val_real();
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    if (!null_value)
      result= protocol->store(nr, decimals, buffer);
    break;
  }
4923 4924
  case MYSQL_TYPE_DOUBLE:
  {
4925
    double nr= val_real();
4926 4927 4928 4929 4930 4931
    if (!null_value)
      result= protocol->store(nr, decimals, buffer);
    break;
  }
  case MYSQL_TYPE_DATETIME:
  case MYSQL_TYPE_DATE:
4932
  case MYSQL_TYPE_TIMESTAMP:
4933 4934
  {
    TIME tm;
4935
    get_date(&tm, TIME_FUZZY_DATE);
4936 4937
    if (!null_value)
    {
4938
      if (f_type == MYSQL_TYPE_DATE)
4939 4940 4941 4942 4943 4944 4945 4946 4947 4948 4949 4950 4951 4952 4953 4954 4955 4956
	return protocol->store_date(&tm);
      else
	result= protocol->store(&tm);
    }
    break;
  }
  case MYSQL_TYPE_TIME:
  {
    TIME tm;
    get_time(&tm);
    if (!null_value)
      result= protocol->store_time(&tm);
    break;
  }
  }
  if (null_value)
    result= protocol->store_null();
  return result;
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}

4959 4960

bool Item_field::send(Protocol *protocol, String *buffer)
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4961
{
4962
  return protocol->store(result_field);
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}

4965

4966 4967 4968 4969 4970 4971 4972 4973 4974 4975 4976 4977 4978 4979 4980 4981
void Item_field::update_null_value() 
{ 
  /* 
    need to set no_errors to prevent warnings about type conversion 
    popping up.
  */
  THD *thd= field->table->in_use;
  int no_errors;

  no_errors= thd->no_errors;
  thd->no_errors= 1;
  Item::update_null_value();
  thd->no_errors= no_errors;
}


4982 4983 4984 4985 4986 4987 4988 4989 4990 4991 4992 4993 4994 4995 4996 4997 4998 4999 5000 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 5012 5013 5014 5015 5016 5017 5018 5019 5020 5021 5022 5023 5024 5025 5026
/*
  Add the field to the select list and substitute it for the reference to
  the field.

  SYNOPSIS
    Item_field::update_value_transformer()
    select_arg      current select

  DESCRIPTION
    If the field doesn't belong to the table being inserted into then it is
    added to the select list, pointer to it is stored in the ref_pointer_array
    of the select and the field itself is substituted for the Item_ref object.
    This is done in order to get correct values from update fields that
    belongs to the SELECT part in the INSERT .. SELECT .. ON DUPLICATE KEY
    UPDATE statement.

  RETURN
    0             if error occured
    ref           if all conditions are met
    this field    otherwise
*/

Item *Item_field::update_value_transformer(byte *select_arg)
{
  SELECT_LEX *select= (SELECT_LEX*)select_arg;
  DBUG_ASSERT(fixed);

  if (field->table != select->context.table_list->table &&
      type() != Item::TRIGGER_FIELD_ITEM)
  {
    List<Item> *all_fields= &select->join->all_fields;
    Item **ref_pointer_array= select->ref_pointer_array;
    int el= all_fields->elements;
    Item_ref *ref;

    ref_pointer_array[el]= (Item*)this;
    all_fields->push_front((Item*)this);
    ref= new Item_ref(&select->context, ref_pointer_array + el,
                      table_name, field_name);
    return ref;
  }
  return this;
}


5027 5028 5029 5030 5031 5032 5033 5034 5035 5036 5037 5038 5039 5040 5041 5042
void Item_field::print(String *str)
{
  if (field && field->table->const_table)
  {
    char buff[MAX_FIELD_WIDTH];
    String tmp(buff,sizeof(buff),str->charset());
    field->val_str(&tmp);
    str->append('\'');
    str->append(tmp);
    str->append('\'');
    return;
  }
  Item_ident::print(str);
}


5043 5044
Item_ref::Item_ref(Name_resolution_context *context_arg,
                   Item **item, const char *table_name_arg,
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5045 5046
                   const char *field_name_arg,
                   bool alias_name_used_arg)
5047 5048
  :Item_ident(context_arg, NullS, table_name_arg, field_name_arg),
   result_field(0), ref(item)
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5049
{
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5050
  alias_name_used= alias_name_used_arg;
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  /*
    This constructor used to create some internals references over fixed items
  */
5054
  if (ref && *ref && (*ref)->fixed)
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    set_properties();
}


5059
/*
5060
  Resolve the name of a reference to a column reference.
5061 5062 5063

  SYNOPSIS
    Item_ref::fix_fields()
5064 5065
    thd       [in]      current thread
    reference [in/out]  view column if this item was resolved to a view column
5066 5067

  DESCRIPTION
5068 5069
    The method resolves the column reference represented by 'this' as a column
    present in one of: GROUP BY clause, SELECT clause, outer queries. It is
5070 5071
    used typically for columns in the HAVING clause which are not under
    aggregate functions.
5072 5073

  NOTES
5074 5075
    The name resolution algorithm used is (where [T_j] is an optional table
    name that qualifies the column name):
5076

5077 5078 5079
      resolve_extended([T_j].col_ref_i)
      {
        Search for a column or derived column named col_ref_i [in table T_j]
5080
        in the SELECT and GROUP clauses of Q.
5081

5082 5083
        if such a column is NOT found AND    // Lookup in outer queries.
           there are outer queries
5084 5085 5086
        {
          for each outer query Q_k beginning from the inner-most one
         {
5087 5088 5089 5090 5091 5092 5093 5094
            Search for a column or derived column named col_ref_i
            [in table T_j] in the SELECT and GROUP clauses of Q_k.

            if such a column is not found AND
               - Q_k is not a group query AND
               - Q_k is not inside an aggregate function
               OR
               - Q_(k-1) is not in a HAVING or SELECT clause of Q_k
5095 5096 5097 5098 5099 5100 5101
            {
              search for a column or derived column named col_ref_i
              [in table T_j] in the FROM clause of Q_k;
            }
          }
        }
      }
5102 5103

    This procedure treats GROUP BY and SELECT clauses as one namespace for
5104 5105 5106
    column references in HAVING. Notice that compared to
    Item_field::fix_fields, here we first search the SELECT and GROUP BY
    clauses, and then we search the FROM clause.
5107

5108 5109 5110
  POSTCONDITION
    Item_ref::ref is 0 or points to a valid item

5111 5112 5113 5114
  RETURN
    TRUE  if error
    FALSE on success
*/
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5115

5116
bool Item_ref::fix_fields(THD *thd, Item **reference)
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5117
{
5118
  enum_parsing_place place= NO_MATTER;
5119
  DBUG_ASSERT(fixed == 0);
5120 5121
  SELECT_LEX *current_sel= thd->lex->current_select;

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5122
  if (!ref || ref == not_found_item)
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5123
  {
5124 5125 5126
    if (!(ref= resolve_ref_in_select_and_group(thd, this,
                                               context->select_lex)))
      goto error;             /* Some error occurred (e.g. ambiguous names). */
5127

5128
    if (ref == not_found_item) /* This reference was not resolved. */
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5129
    {
5130 5131
      Name_resolution_context *last_checked_context= context;
      Name_resolution_context *outer_context= context->outer_context;
5132 5133 5134
      Field *from_field;
      ref= 0;

5135
      if (!outer_context)
5136 5137 5138 5139
      {
        /* The current reference cannot be resolved in this query. */
        my_error(ER_BAD_FIELD_ERROR,MYF(0),
                 this->full_name(), current_thd->where);
5140
        goto error;
5141
      }
5142

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5143
      /*
5144 5145 5146
        If there is an outer context (select), and it is not a derived table
        (which do not support the use of outer fields for now), try to
        resolve this reference in the outer select(s).
5147

5148 5149 5150
        We treat each subselect as a separate namespace, so that different
        subselects may contain columns with the same names. The subselects are
        searched starting from the innermost.
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5151
      */
5152 5153
      from_field= (Field*) not_found_field;

5154
      do
5155
      {
5156 5157 5158 5159
        SELECT_LEX *select= outer_context->select_lex;
        Item_subselect *prev_subselect_item=
          last_checked_context->select_lex->master_unit()->item;
        last_checked_context= outer_context;
5160

5161
        /* Search in the SELECT and GROUP lists of the outer select. */
5162
        if (outer_context->resolve_in_select_list)
5163
        {
5164 5165
          if (!(ref= resolve_ref_in_select_and_group(thd, this, select)))
            goto error; /* Some error occurred (e.g. ambiguous names). */
5166
          if (ref != not_found_item)
5167
          {
5168 5169 5170 5171
            DBUG_ASSERT(*ref && (*ref)->fixed);
            prev_subselect_item->used_tables_cache|= (*ref)->used_tables();
            prev_subselect_item->const_item_cache&= (*ref)->const_item();
            break;
5172 5173
          }
          /*
5174 5175 5176
            Set ref to 0 to ensure that we get an error in case we replaced
            this item with another item and still use this item in some
            other place of the parse tree.
5177
          */
5178
          ref= 0;
5179
        }
5180

5181 5182 5183 5184 5185
        place= prev_subselect_item->parsing_place;
        /*
          Check table fields only if the subquery is used somewhere out of
          HAVING or the outer SELECT does not use grouping (i.e. tables are
          accessible).
5186
          TODO:
5187 5188 5189 5190 5191 5192
          Here we could first find the field anyway, and then test this
          condition, so that we can give a better error message -
          ER_WRONG_FIELD_WITH_GROUP, instead of the less informative
          ER_BAD_FIELD_ERROR which we produce now.
        */
        if ((place != IN_HAVING ||
5193 5194
             (!select->with_sum_func &&
              select->group_list.elements == 0)))
5195
        {
5196
          /*
5197 5198 5199
            In case of view, find_field_in_tables() write pointer to view
            field expression to 'reference', i.e. it substitute that
            expression instead of this Item_ref
5200
          */
5201
          from_field= find_field_in_tables(thd, this,
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5202 5203 5204 5205
                                           outer_context->
                                             first_name_resolution_table,
                                           outer_context->
                                             last_name_resolution_table,
5206 5207
                                           reference,
                                           IGNORE_EXCEPT_NON_UNIQUE,
5208
                                           TRUE, TRUE);
5209
          if (! from_field)
5210
            goto error;
5211
          if (from_field == view_ref_found)
5212
          {
5213
            Item::Type refer_type= (*reference)->type();
5214 5215 5216 5217 5218
            prev_subselect_item->used_tables_cache|=
              (*reference)->used_tables();
            prev_subselect_item->const_item_cache&=
              (*reference)->const_item();
            DBUG_ASSERT((*reference)->type() == REF_ITEM);
5219 5220
            mark_as_dependent(thd, last_checked_context->select_lex,
                              context->select_lex, this,
5221 5222
                              ((refer_type == REF_ITEM ||
                                refer_type == FIELD_ITEM) ?
5223 5224 5225 5226 5227 5228
                               (Item_ident*) (*reference) :
                               0));
            /*
              view reference found, we substituted it instead of this
              Item, so can quit
            */
5229 5230
            return FALSE;
          }
5231 5232
          if (from_field != not_found_field)
          {
5233 5234 5235 5236 5237 5238 5239 5240 5241 5242 5243 5244 5245 5246 5247 5248 5249 5250 5251
            if (cached_table && cached_table->select_lex &&
                outer_context->select_lex &&
                cached_table->select_lex != outer_context->select_lex)
            {
              /*
                Due to cache, find_field_in_tables() can return field which
                doesn't belong to provided outer_context. In this case we have
                to find proper field context in order to fix field correcly.
              */
              do
              {
                outer_context= outer_context->outer_context;
                select= outer_context->select_lex;
                prev_subselect_item=
                  last_checked_context->select_lex->master_unit()->item;
                last_checked_context= outer_context;
              } while (outer_context && outer_context->select_lex &&
                       cached_table->select_lex != outer_context->select_lex);
            }
5252 5253 5254 5255
            prev_subselect_item->used_tables_cache|= from_field->table->map;
            prev_subselect_item->const_item_cache= 0;
            break;
          }
5256
        }
5257 5258 5259 5260 5261 5262
        DBUG_ASSERT(from_field == not_found_field);

        /* Reference is not found => depend on outer (or just error). */
        prev_subselect_item->used_tables_cache|= OUTER_REF_TABLE_BIT;
        prev_subselect_item->const_item_cache= 0;

5263 5264
        outer_context= outer_context->outer_context;
      } while (outer_context);
5265 5266 5267

      DBUG_ASSERT(from_field != 0 && from_field != view_ref_found);
      if (from_field != not_found_field)
5268
      {
5269 5270
        Item_field* fld;
        if (!(fld= new Item_field(from_field)))
5271
          goto error;
5272
        thd->change_item_tree(reference, fld);
5273 5274
        mark_as_dependent(thd, last_checked_context->select_lex,
                          thd->lex->current_select, this, fld);
5275 5276 5277 5278 5279 5280
        return FALSE;
      }
      if (ref == 0)
      {
        /* The item was not a table field and not a reference */
        my_error(ER_BAD_FIELD_ERROR, MYF(0),
5281
                 this->full_name(), current_thd->where);
5282
        goto error;
5283
      }
5284 5285
      /* Should be checked in resolve_ref_in_select_and_group(). */
      DBUG_ASSERT(*ref && (*ref)->fixed);
5286 5287
      mark_as_dependent(thd, last_checked_context->select_lex,
                        context->select_lex, this, this);
5288
    }
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5289
  }
5290

5291
  DBUG_ASSERT(*ref);
5292
  /*
5293 5294 5295
    Check if this is an incorrect reference in a group function or forward
    reference. Do not issue an error if this is an unnamed reference inside an
    aggregate function.
5296
  */
5297
  if (((*ref)->with_sum_func && name &&
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5298 5299
       !(current_sel->linkage != GLOBAL_OPTIONS_TYPE &&
         current_sel->having_fix_field)) ||
5300 5301
      !(*ref)->fixed)
  {
5302 5303 5304 5305
    my_error(ER_ILLEGAL_REFERENCE, MYF(0),
             name, ((*ref)->with_sum_func?
                    "reference to group function":
                    "forward reference in item list"));
5306
    goto error;
5307
  }
5308 5309 5310

  set_properties();

5311
  if ((*ref)->check_cols(1))
5312
    goto error;
5313
  return FALSE;
5314 5315 5316 5317

error:
  context->process_error(thd);
  return TRUE;
5318 5319
}

5320

5321 5322
void Item_ref::set_properties()
{
5323 5324 5325
  max_length= (*ref)->max_length;
  maybe_null= (*ref)->maybe_null;
  decimals=   (*ref)->decimals;
5326
  collation.set((*ref)->collation);
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5327 5328 5329 5330
  /*
    We have to remember if we refer to a sum function, to ensure that
    split_sum_func() doesn't try to change the reference.
  */
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5331
  with_sum_func= (*ref)->with_sum_func;
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5332
  unsigned_flag= (*ref)->unsigned_flag;
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5333 5334 5335
  fixed= 1;
  if (alias_name_used)
    return;
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5336 5337 5338 5339
  if ((*ref)->type() == FIELD_ITEM)
    alias_name_used= ((Item_ident *) (*ref))->alias_name_used;
  else
    alias_name_used= TRUE; // it is not field, so it is was resolved by alias
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5340 5341
}

5342

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5343 5344
void Item_ref::cleanup()
{
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5345
  DBUG_ENTER("Item_ref::cleanup");
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5346
  Item_ident::cleanup();
5347
  result_field= 0;
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5348
  DBUG_VOID_RETURN;
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5349 5350 5351
}


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5352 5353
void Item_ref::print(String *str)
{
5354
  if (ref)
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5355 5356
  {
    if ((*ref)->type() != Item::CACHE_ITEM && ref_type() != VIEW_REF &&
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        !table_name && name && alias_name_used)
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    {
      THD *thd= current_thd;
      append_identifier(thd, str, name, (uint) strlen(name));
    }
    else
      (*ref)->print(str);
  }
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  else
    Item_ident::print(str);
}


5370 5371 5372 5373 5374 5375 5376 5377
bool Item_ref::send(Protocol *prot, String *tmp)
{
  if (result_field)
    return prot->store(result_field);
  return (*ref)->send(prot, tmp);
}


5378 5379 5380 5381 5382 5383 5384 5385
double Item_ref::val_result()
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
      return 0.0;
    return result_field->val_real();
  }
5386
  return val_real();
5387 5388 5389 5390 5391 5392 5393 5394
}


longlong Item_ref::val_int_result()
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
5395
      return 0;
5396 5397 5398 5399 5400 5401 5402 5403 5404 5405 5406 5407 5408 5409 5410 5411 5412 5413 5414
    return result_field->val_int();
  }
  return val_int();
}


String *Item_ref::str_result(String* str)
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
      return 0;
    str->set_charset(str_value.charset());
    return result_field->val_str(str, &str_value);
  }
  return val_str(str);
}


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my_decimal *Item_ref::val_decimal_result(my_decimal *decimal_value)
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
      return 0;
    return result_field->val_decimal(decimal_value);
  }
  return val_decimal(decimal_value);
}


bool Item_ref::val_bool_result()
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
      return 0;
5433
    switch (result_field->result_type()) {
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5434
    case INT_RESULT:
5435
      return result_field->val_int() != 0;
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5436
    case DECIMAL_RESULT:
5437 5438 5439 5440 5441 5442 5443
    {
      my_decimal decimal_value;
      my_decimal *val= result_field->val_decimal(&decimal_value);
      if (val)
        return !my_decimal_is_zero(val);
      return 0;
    }
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5444 5445 5446 5447 5448 5449 5450 5451 5452 5453 5454 5455 5456 5457 5458 5459 5460 5461 5462 5463 5464 5465 5466 5467 5468 5469 5470 5471 5472 5473 5474 5475 5476 5477 5478 5479 5480 5481 5482 5483 5484 5485 5486 5487 5488 5489 5490 5491 5492 5493 5494
    case REAL_RESULT:
    case STRING_RESULT:
      return result_field->val_real() != 0.0;
    case ROW_RESULT:
    default:
      DBUG_ASSERT(0);
    }
  }
  return val_bool();
}


double Item_ref::val_real()
{
  DBUG_ASSERT(fixed);
  double tmp=(*ref)->val_result();
  null_value=(*ref)->null_value;
  return tmp;
}


longlong Item_ref::val_int()
{
  DBUG_ASSERT(fixed);
  longlong tmp=(*ref)->val_int_result();
  null_value=(*ref)->null_value;
  return tmp;
}


bool Item_ref::val_bool()
{
  DBUG_ASSERT(fixed);
  bool tmp= (*ref)->val_bool_result();
  null_value= (*ref)->null_value;
  return tmp;
}


String *Item_ref::val_str(String* tmp)
{
  DBUG_ASSERT(fixed);
  tmp=(*ref)->str_result(tmp);
  null_value=(*ref)->null_value;
  return tmp;
}


bool Item_ref::is_null()
{
  DBUG_ASSERT(fixed);
5495
  return (*ref)->is_null();
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}


bool Item_ref::get_date(TIME *ltime,uint fuzzydate)
{
  return (null_value=(*ref)->get_date_result(ltime,fuzzydate));
}


my_decimal *Item_ref::val_decimal(my_decimal *decimal_value)
{
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5507
  my_decimal *val= (*ref)->val_decimal_result(decimal_value);
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  null_value= (*ref)->null_value;
  return val;
}

5512 5513 5514
int Item_ref::save_in_field(Field *to, bool no_conversions)
{
  int res;
5515
  DBUG_ASSERT(!result_field);
5516 5517 5518 5519 5520
  res= (*ref)->save_in_field(to, no_conversions);
  null_value= (*ref)->null_value;
  return res;
}

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void Item_ref::save_org_in_field(Field *field)
{
  (*ref)->save_org_in_field(field);
}


5528 5529 5530 5531 5532 5533 5534 5535 5536 5537
void Item_ref::make_field(Send_field *field)
{
  (*ref)->make_field(field);
  /* Non-zero in case of a view */
  if (name)
    field->col_name= name;
  if (table_name)
    field->table_name= table_name;
  if (db_name)
    field->db_name= db_name;
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5538
}
5539 5540


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void Item_ref_null_helper::print(String *str)
{
5543
  str->append(STRING_WITH_LEN("<ref_null_helper>("));
5544
  if (ref)
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    (*ref)->print(str);
  else
    str->append('?');
  str->append(')');
}


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double Item_direct_ref::val_real()
{
  double tmp=(*ref)->val_real();
  null_value=(*ref)->null_value;
  return tmp;
}


longlong Item_direct_ref::val_int()
{
  longlong tmp=(*ref)->val_int();
  null_value=(*ref)->null_value;
  return tmp;
}


String *Item_direct_ref::val_str(String* tmp)
{
  tmp=(*ref)->val_str(tmp);
  null_value=(*ref)->null_value;
  return tmp;
}


my_decimal *Item_direct_ref::val_decimal(my_decimal *decimal_value)
{
  my_decimal *tmp= (*ref)->val_decimal(decimal_value);
  null_value=(*ref)->null_value;
  return tmp;
}


bool Item_direct_ref::val_bool()
{
  bool tmp= (*ref)->val_bool();
  null_value=(*ref)->null_value;
  return tmp;
}


bool Item_direct_ref::is_null()
{
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  return (*ref)->is_null();
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}


bool Item_direct_ref::get_date(TIME *ltime,uint fuzzydate)
{
  return (null_value=(*ref)->get_date(ltime,fuzzydate));
}


5604
/*
5605
  Prepare referenced field then call usual Item_direct_ref::fix_fields
5606 5607 5608 5609 5610 5611 5612 5613 5614 5615 5616 5617 5618 5619 5620 5621 5622 5623 5624 5625 5626 5627

  SYNOPSIS
    Item_direct_view_ref::fix_fields()
    thd         thread handler
    reference   reference on reference where this item stored

  RETURN
    FALSE   OK
    TRUE    Error
*/

bool Item_direct_view_ref::fix_fields(THD *thd, Item **reference)
{
  /* view fild reference must be defined */
  DBUG_ASSERT(*ref);
  /* (*ref)->check_cols() will be made in Item_direct_ref::fix_fields */
  if (!(*ref)->fixed &&
      ((*ref)->fix_fields(thd, ref)))
    return TRUE;
  return Item_direct_ref::fix_fields(thd, reference);
}

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/*
  Prepare referenced outer field then call usual Item_direct_ref::fix_fields

  SYNOPSIS
    Item_outer_ref::fix_fields()
    thd         thread handler
    reference   reference on reference where this item stored

  RETURN
    FALSE   OK
    TRUE    Error
*/

bool Item_outer_ref::fix_fields(THD *thd, Item **reference)
{
  DBUG_ASSERT(*ref);
  /* outer_field->check_cols() will be made in Item_direct_ref::fix_fields */
  outer_field->fixed_as_field= 1;
  if (!outer_field->fixed &&
      (outer_field->fix_fields(thd, reference)))
    return TRUE;
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  table_name= outer_field->table_name;
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  return Item_direct_ref::fix_fields(thd, reference);
}

5653
/*
5654
  Compare two view column references for equality.
5655 5656 5657 5658 5659 5660 5661

  SYNOPSIS
    Item_direct_view_ref::eq()
    item        item to compare with
    binary_cmp  make binary comparison

  DESCRIPTION
5662 5663
    A view column reference is considered equal to another column
    reference if the second one is a view column and if both column
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    references resolve to the same item. It is assumed that both
    items are of the same type.
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  RETURN
    TRUE    Referenced item is equal to given item
    FALSE   otherwise
*/


bool Item_direct_view_ref::eq(const Item *item, bool binary_cmp) const
{
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  if (item->type() == REF_ITEM)
  {
    Item_ref *item_ref= (Item_ref*) item;
    if (item_ref->ref_type() == VIEW_REF)
    {
      Item *item_ref_ref= *(item_ref->ref);
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      DBUG_ASSERT((*ref)->real_item()->type() == 
                  item_ref_ref->real_item()->type());
5683
      return ((*ref)->real_item() == item_ref_ref->real_item());
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    }
  }
  return FALSE;
5687
}
5688

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bool Item_default_value::eq(const Item *item, bool binary_cmp) const
{
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  return item->type() == DEFAULT_VALUE_ITEM && 
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    ((Item_default_value *)item)->arg->eq(arg, binary_cmp);
}

5695

5696
bool Item_default_value::fix_fields(THD *thd, Item **items)
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{
5698
  Item *real_arg;
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  Item_field *field_arg;
  Field *def_field;
5701
  DBUG_ASSERT(fixed == 0);
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  if (!arg)
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  {
    fixed= 1;
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    return FALSE;
5707
  }
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  if (!arg->fixed && arg->fix_fields(thd, &arg))
    goto error;

5711

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  real_arg= arg->real_item();
  if (real_arg->type() != FIELD_ITEM)
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  {
5715
    my_error(ER_NO_DEFAULT_FOR_FIELD, MYF(0), arg->name);
5716
    goto error;
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  }
5718

5719
  field_arg= (Item_field *)real_arg;
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  if (field_arg->field->flags & NO_DEFAULT_VALUE_FLAG)
  {
5722
    my_error(ER_NO_DEFAULT_FOR_FIELD, MYF(0), field_arg->field->field_name);
5723
    goto error;
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  }
  if (!(def_field= (Field*) sql_alloc(field_arg->field->size_of())))
5726
    goto error;
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  memcpy(def_field, field_arg->field, field_arg->field->size_of());
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  def_field->move_field_offset((my_ptrdiff_t)
                               (def_field->table->s->default_values -
                                def_field->table->record[0]));
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  set_field(def_field);
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  return FALSE;
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error:
  context->process_error(thd);
  return TRUE;
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}

5739

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void Item_default_value::print(String *str)
{
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  if (!arg)
  {
5744
    str->append(STRING_WITH_LEN("default"));
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    return;
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  }
5747
  str->append(STRING_WITH_LEN("default("));
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  arg->print(str);
  str->append(')');
}
5751

5752 5753 5754 5755 5756 5757 5758

int Item_default_value::save_in_field(Field *field_arg, bool no_conversions)
{
  if (!arg)
  {
    if (field_arg->flags & NO_DEFAULT_VALUE_FLAG)
    {
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      if (field_arg->reset())
      {
        my_message(ER_CANT_CREATE_GEOMETRY_OBJECT,
                   ER(ER_CANT_CREATE_GEOMETRY_OBJECT), MYF(0));
        return -1;
      }

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      if (context->error_processor == &view_error_processor)
      {
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        TABLE_LIST *view= cached_table->top_table();
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        push_warning_printf(field_arg->table->in_use,
                            MYSQL_ERROR::WARN_LEVEL_WARN,
                            ER_NO_DEFAULT_FOR_VIEW_FIELD,
                            ER(ER_NO_DEFAULT_FOR_VIEW_FIELD),
                            view->view_db.str,
                            view->view_name.str);
      }
      else
      {
        push_warning_printf(field_arg->table->in_use,
                            MYSQL_ERROR::WARN_LEVEL_WARN,
                            ER_NO_DEFAULT_FOR_FIELD,
                            ER(ER_NO_DEFAULT_FOR_FIELD),
                            field_arg->field_name);
      }
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      return 1;
    }
    field_arg->set_default();
    return 0;
  }
  return Item_field::save_in_field(field_arg, no_conversions);
}


5793
/* 
5794 5795
  This method like the walk method traverses the item tree, but at the
  same time it can replace some nodes in the tree
5796
*/ 
5797

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Item *Item_default_value::transform(Item_transformer transformer, byte *args)
{
  DBUG_ASSERT(!current_thd->is_stmt_prepare());

  Item *new_item= arg->transform(transformer, args);
  if (!new_item)
    return 0;

  /*
    THD::change_item_tree() should be called only if the tree was
    really transformed, i.e. when a new item has been created.
    Otherwise we'll be allocating a lot of unnecessary memory for
    change records at each execution.
  */
  if (arg != new_item)
    current_thd->change_item_tree(&arg, new_item);
  return (this->*transformer)(args);
}


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bool Item_insert_value::eq(const Item *item, bool binary_cmp) const
{
  return item->type() == INSERT_VALUE_ITEM &&
    ((Item_default_value *)item)->arg->eq(arg, binary_cmp);
}


5825
bool Item_insert_value::fix_fields(THD *thd, Item **items)
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{
5827
  DBUG_ASSERT(fixed == 0);
5828
  /* We should only check that arg is in first table */
5829
  if (!arg->fixed)
5830
  {
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    bool res;
    st_table_list *orig_next_table= context->last_name_resolution_table;
    context->last_name_resolution_table= context->first_name_resolution_table;
    res= arg->fix_fields(thd, &arg);
5835
    context->last_name_resolution_table= orig_next_table;
5836 5837
    if (res)
      return TRUE;
5838
  }
5839

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  if (arg->type() == REF_ITEM)
  {
    Item_ref *ref= (Item_ref *)arg;
    if (ref->ref[0]->type() != FIELD_ITEM)
    {
5845
      my_error(ER_BAD_FIELD_ERROR, MYF(0), "", "VALUES() function");
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      return TRUE;
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    }
    arg= ref->ref[0];
  }
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  /*
    According to our SQL grammar, VALUES() function can reference
    only to a column.
  */
  DBUG_ASSERT(arg->type() == FIELD_ITEM);

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  Item_field *field_arg= (Item_field *)arg;
5857

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  if (field_arg->field->table->insert_values)
  {
    Field *def_field= (Field*) sql_alloc(field_arg->field->size_of());
    if (!def_field)
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      return TRUE;
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    memcpy(def_field, field_arg->field, field_arg->field->size_of());
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    def_field->move_field_offset((my_ptrdiff_t)
                                 (def_field->table->insert_values -
                                  def_field->table->record[0]));
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    set_field(def_field);
  }
  else
  {
5871
    Field *tmp_field= field_arg->field;
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    /* charset doesn't matter here, it's to avoid sigsegv only */
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    tmp_field= new Field_null(0, 0, Field::NONE, field_arg->field->field_name,
                          &my_charset_bin);
    if (tmp_field)
    {
      tmp_field->init(field_arg->field->table);
      set_field(tmp_field);
    }
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  }
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  return FALSE;
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}

void Item_insert_value::print(String *str)
{
5886
  str->append(STRING_WITH_LEN("values("));
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  arg->print(str);
  str->append(')');
}

5891 5892

/*
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  Find index of Field object which will be appropriate for item
  representing field of row being changed in trigger.
5895 5896 5897 5898 5899

  SYNOPSIS
    setup_field()
      thd   - current thread context
      table - table of trigger (and where we looking for fields)
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      table_grant_info - GRANT_INFO of the subject table
5901 5902 5903

  NOTE
    This function does almost the same as fix_fields() for Item_field
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    but is invoked right after trigger definition parsing. Since at
    this stage we can't say exactly what Field object (corresponding
    to TABLE::record[0] or TABLE::record[1]) should be bound to this
    Item, we only find out index of the Field and then select concrete
    Field object in fix_fields() (by that time Table_trigger_list::old_field/
    new_field should point to proper array of Fields).
    It also binds Item_trigger_field to Table_triggers_list object for
    table of trigger which uses this item.
5912
*/
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void Item_trigger_field::setup_field(THD *thd, TABLE *table,
                                     GRANT_INFO *table_grant_info)
5916
{
5917
  /*
5918 5919 5920 5921 5922
    It is too early to mark fields used here, because before execution
    of statement that will invoke trigger other statements may use same
    TABLE object, so all such mark-up will be wiped out.
    So instead we do it in Table_triggers_list::mark_fields_used()
    method which is called during execution of these statements.
5923
  */
5924 5925
  enum_mark_columns save_mark_used_columns= thd->mark_used_columns;
  thd->mark_used_columns= MARK_COLUMNS_NONE;
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  /*
    Try to find field by its name and if it will be found
    set field_idx properly.
  */
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  (void)find_field_in_table(thd, table, field_name, (uint) strlen(field_name),
5931
                            0, &field_idx);
5932
  thd->mark_used_columns= save_mark_used_columns;
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  triggers= table->triggers;
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  table_grants= table_grant_info;
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}


bool Item_trigger_field::eq(const Item *item, bool binary_cmp) const
{
  return item->type() == TRIGGER_FIELD_ITEM &&
         row_version == ((Item_trigger_field *)item)->row_version &&
         !my_strcasecmp(system_charset_info, field_name,
                        ((Item_trigger_field *)item)->field_name);
}


5947
void Item_trigger_field::set_required_privilege(bool rw)
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{
  /*
    Require SELECT and UPDATE privilege if this field will be read and
    set, and only UPDATE privilege for setting the field.
  */
  want_privilege= (rw ? SELECT_ACL | UPDATE_ACL : UPDATE_ACL);
}


5957
bool Item_trigger_field::set_value(THD *thd, sp_rcontext * /*ctx*/, Item **it)
5958
{
5959
  Item *item= sp_prepare_func_item(thd, it);
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  return (!item || (!fixed && fix_fields(thd, 0)) ||
          (item->save_in_field(field, 0) < 0));
}


5966
bool Item_trigger_field::fix_fields(THD *thd, Item **items)
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{
  /*
    Since trigger is object tightly associated with TABLE object most
    of its set up can be performed during trigger loading i.e. trigger
    parsing! So we have little to do in fix_fields. :)
  */
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5974
  DBUG_ASSERT(fixed == 0);
5975

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  /* Set field. */

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  if (field_idx != (uint)-1)
5979
  {
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#ifndef NO_EMBEDDED_ACCESS_CHECKS
    /*
      Check access privileges for the subject table. We check privileges only
      in runtime.
    */

    if (table_grants)
    {
5988
      table_grants->want_privilege= want_privilege;
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      if (check_grant_column(thd, table_grants, triggers->trigger_table->s->db.str,
                             triggers->trigger_table->s->table_name.str, field_name,
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                             strlen(field_name), thd->security_ctx))
        return TRUE;
    }
#endif // NO_EMBEDDED_ACCESS_CHECKS

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    field= (row_version == OLD_ROW) ? triggers->old_field[field_idx] :
                                      triggers->new_field[field_idx];
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    set_field(field);
    fixed= 1;
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    return FALSE;
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  }

  my_error(ER_BAD_FIELD_ERROR, MYF(0), field_name,
           (row_version == NEW_ROW) ? "NEW" : "OLD");
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  return TRUE;
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}


void Item_trigger_field::print(String *str)
{
  str->append((row_version == NEW_ROW) ? "NEW" : "OLD", 3);
  str->append('.');
  str->append(field_name);
}


void Item_trigger_field::cleanup()
{
6020
  want_privilege= original_privilege;
6021 6022 6023 6024 6025 6026 6027 6028
  /*
    Since special nature of Item_trigger_field we should not do most of
    things from Item_field::cleanup() or Item_ident::cleanup() here.
  */
  Item::cleanup();
}


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Item_result item_cmp_type(Item_result a,Item_result b)
{
  if (a == STRING_RESULT && b == STRING_RESULT)
    return STRING_RESULT;
6033
  if (a == INT_RESULT && b == INT_RESULT)
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    return INT_RESULT;
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  else if (a == ROW_RESULT || b == ROW_RESULT)
    return ROW_RESULT;
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  if ((a == INT_RESULT || a == DECIMAL_RESULT) &&
      (b == INT_RESULT || b == DECIMAL_RESULT))
    return DECIMAL_RESULT;
6040
  return REAL_RESULT;
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}


6044
void resolve_const_item(THD *thd, Item **ref, Item *comp_item)
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{
6046
  Item *item= *ref;
6047
  Item *new_item= NULL;
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  if (item->basic_const_item())
6049
    return;                                     // Can't be better
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  Item_result res_type=item_cmp_type(comp_item->result_type(),
				     item->result_type());
  char *name=item->name;			// Alloced by sql_alloc

6054
  switch (res_type) {
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  case STRING_RESULT:
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  {
    char buff[MAX_FIELD_WIDTH];
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    String tmp(buff,sizeof(buff),&my_charset_bin),*result;
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    result=item->val_str(&tmp);
    if (item->null_value)
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      new_item= new Item_null(name);
    else
    {
      uint length= result->length();
      char *tmp_str= sql_strmake(result->ptr(), length);
      new_item= new Item_string(name, tmp_str, length, result->charset());
    }
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    break;
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  }
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  case INT_RESULT:
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  {
    longlong result=item->val_int();
    uint length=item->max_length;
    bool null_value=item->null_value;
6075 6076
    new_item= (null_value ? (Item*) new Item_null(name) :
               (Item*) new Item_int(name, result, length));
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    break;
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  }
6079
  case ROW_RESULT:
6080
  if (item->type() == Item::ROW_ITEM && comp_item->type() == Item::ROW_ITEM)
6081
  {
6082 6083 6084 6085 6086 6087 6088 6089
    /*
      Substitute constants only in Item_rows. Don't affect other Items
      with ROW_RESULT (eg Item_singlerow_subselect).

      For such Items more optimal is to detect if it is constant and replace
      it with Item_row. This would optimize queries like this:
      SELECT * FROM t1 WHERE (a,b) = (SELECT a,b FROM t2 LIMIT 1);
    */
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    Item_row *item_row= (Item_row*) item;
    Item_row *comp_item_row= (Item_row*) comp_item;
    uint col;
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    new_item= 0;
    /*
      If item and comp_item are both Item_rows and have same number of cols
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      then process items in Item_row one by one.
      We can't ignore NULL values here as this item may be used with <=>, in
      which case NULL's are significant.
6099
    */
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    DBUG_ASSERT(item->result_type() == comp_item->result_type());
    DBUG_ASSERT(item_row->cols() == comp_item_row->cols());
    col= item_row->cols();
    while (col-- > 0)
6104 6105
      resolve_const_item(thd, item_row->addr(col),
                         comp_item_row->element_index(col));
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    break;
6107
  }
6108
  /* Fallthrough */
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  case REAL_RESULT:
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  {						// It must REAL_RESULT
6111
    double result= item->val_real();
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    uint length=item->max_length,decimals=item->decimals;
    bool null_value=item->null_value;
6114
    new_item= (null_value ? (Item*) new Item_null(name) : (Item*)
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               new Item_float(name, result, decimals, length));
    break;
  }
  case DECIMAL_RESULT:
  {
    my_decimal decimal_value;
    my_decimal *result= item->val_decimal(&decimal_value);
    uint length= item->max_length, decimals= item->decimals;
    bool null_value= item->null_value;
    new_item= (null_value ?
               (Item*) new Item_null(name) :
               (Item*) new Item_decimal(name, result, length, decimals));
    break;
  }
  default:
    DBUG_ASSERT(0);
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  }
6132 6133
  if (new_item)
    thd->change_item_tree(ref, new_item);
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}

/*
  Return true if the value stored in the field is equal to the const item
  We need to use this on the range optimizer because in some cases
  we can't store the value in the field without some precision/character loss.
*/

bool field_is_equal_to_item(Field *field,Item *item)
{

  Item_result res_type=item_cmp_type(field->result_type(),
				     item->result_type());
  if (res_type == STRING_RESULT)
  {
    char item_buff[MAX_FIELD_WIDTH];
    char field_buff[MAX_FIELD_WIDTH];
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    String item_tmp(item_buff,sizeof(item_buff),&my_charset_bin),*item_result;
    String field_tmp(field_buff,sizeof(field_buff),&my_charset_bin);
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    item_result=item->val_str(&item_tmp);
    if (item->null_value)
      return 1;					// This must be true
6156
    field->val_str(&field_tmp);
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    return !stringcmp(&field_tmp,item_result);
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  }
  if (res_type == INT_RESULT)
    return 1;					// Both where of type int
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  if (res_type == DECIMAL_RESULT)
  {
    my_decimal item_buf, *item_val,
               field_buf, *field_val;
    item_val= item->val_decimal(&item_buf);
    if (item->null_value)
      return 1;					// This must be true
    field_val= field->val_decimal(&field_buf);
    return !my_decimal_cmp(item_val, field_val);
  }
6171
  double result= item->val_real();
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  if (item->null_value)
    return 1;
  return result == field->val_real();
}

6177 6178
Item_cache* Item_cache::get_cache(Item_result type)
{
6179
  switch (type) {
6180 6181 6182 6183
  case INT_RESULT:
    return new Item_cache_int();
  case REAL_RESULT:
    return new Item_cache_real();
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  case DECIMAL_RESULT:
    return new Item_cache_decimal();
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  case STRING_RESULT:
    return new Item_cache_str();
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  case ROW_RESULT:
    return new Item_cache_row();
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  default:
    // should never be in real life
    DBUG_ASSERT(0);
    return 0;
  }
}

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void Item_cache::print(String *str)
{
6200
  str->append(STRING_WITH_LEN("<cache>("));
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  if (example)
    example->print(str);
  else
    Item::print(str);
  str->append(')');
}


void Item_cache_int::store(Item *item)
{
  value= item->val_int_result();
  null_value= item->null_value;
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  unsigned_flag= item->unsigned_flag;
}


String *Item_cache_int::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  str->set(value, default_charset());
  return str;
}


my_decimal *Item_cache_int::val_decimal(my_decimal *decimal_val)
{
  DBUG_ASSERT(fixed == 1);
  int2my_decimal(E_DEC_FATAL_ERROR, value, unsigned_flag, decimal_val);
  return decimal_val;
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}


void Item_cache_real::store(Item *item)
{
  value= item->val_result();
  null_value= item->null_value;
}


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longlong Item_cache_real::val_int()
{
  DBUG_ASSERT(fixed == 1);
6243
  return (longlong) rint(value);
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}


String* Item_cache_real::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
6250
  str->set_real(value, decimals, default_charset());
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  return str;
}


my_decimal *Item_cache_real::val_decimal(my_decimal *decimal_val)
{
  DBUG_ASSERT(fixed == 1);
  double2my_decimal(E_DEC_FATAL_ERROR, value, decimal_val);
  return decimal_val;
}


void Item_cache_decimal::store(Item *item)
{
  my_decimal *val= item->val_decimal_result(&decimal_value);
6266
  if (!(null_value= item->null_value) && val != &decimal_value)
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    my_decimal2decimal(val, &decimal_value);
}

double Item_cache_decimal::val_real()
{
  DBUG_ASSERT(fixed);
  double res;
  my_decimal2double(E_DEC_FATAL_ERROR, &decimal_value, &res);
  return res;
}

longlong Item_cache_decimal::val_int()
{
  DBUG_ASSERT(fixed);
  longlong res;
  my_decimal2int(E_DEC_FATAL_ERROR, &decimal_value, unsigned_flag, &res);
  return res;
}

String* Item_cache_decimal::val_str(String *str)
{
  DBUG_ASSERT(fixed);
  my_decimal_round(E_DEC_FATAL_ERROR, &decimal_value, decimals, FALSE,
                   &decimal_value);
  my_decimal2string(E_DEC_FATAL_ERROR, &decimal_value, 0, 0, 0, str);
  return str;
}

my_decimal *Item_cache_decimal::val_decimal(my_decimal *val)
{
  DBUG_ASSERT(fixed);
  return &decimal_value;
}


6302 6303
void Item_cache_str::store(Item *item)
{
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  value_buff.set(buffer, sizeof(buffer), item->collation.collation);
6305
  value= item->str_result(&value_buff);
6306 6307
  if ((null_value= item->null_value))
    value= 0;
6308
  else if (value != &value_buff)
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  {
    /*
      We copy string value to avoid changing value if 'item' is table field
      in queries like following (where t1.c is varchar):
      select a, 
             (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a'),
             (select c from t1 where a=t2.a)
        from t2;
    */
6318 6319
    value_buff.copy(*value);
    value= &value_buff;
6320 6321
  }
}
6322

6323
double Item_cache_str::val_real()
6324 6325
{
  DBUG_ASSERT(fixed == 1);
6326 6327
  int err_not_used;
  char *end_not_used;
6328
  if (value)
6329
    return my_strntod(value->charset(), (char*) value->ptr(),
6330 6331
		      value->length(), &end_not_used, &err_not_used);
  return (double) 0;
6332
}
6333 6334


6335 6336
longlong Item_cache_str::val_int()
{
6337
  DBUG_ASSERT(fixed == 1);
6338
  int err;
6339 6340
  if (value)
    return my_strntoll(value->charset(), value->ptr(),
6341
		       value->length(), 10, (char**) 0, &err);
6342 6343 6344
  else
    return (longlong)0;
}
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my_decimal *Item_cache_str::val_decimal(my_decimal *decimal_val)
{
  DBUG_ASSERT(fixed == 1);
  if (value)
    string2my_decimal(E_DEC_FATAL_ERROR, value, decimal_val);
  else
    decimal_val= 0;
  return decimal_val;
}

6356

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bool Item_cache_row::allocate(uint num)
{
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  item_count= num;
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  THD *thd= current_thd;
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  return (!(values= 
	    (Item_cache **) thd->calloc(sizeof(Item_cache *)*item_count)));
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}

6365

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bool Item_cache_row::setup(Item * item)
{
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  example= item;
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  if (!values && allocate(item->cols()))
    return 1;
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  for (uint i= 0; i < item_count; i++)
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  {
6373
    Item *el= item->element_index(i);
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    Item_cache *tmp;
    if (!(tmp= values[i]= Item_cache::get_cache(el->result_type())))
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      return 1;
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    tmp->setup(el);
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  }
  return 0;
}

6382

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void Item_cache_row::store(Item * item)
{
  null_value= 0;
  item->bring_value();
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  for (uint i= 0; i < item_count; i++)
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  {
6389
    values[i]->store(item->element_index(i));
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    null_value|= values[i]->null_value;
  }
}

6394

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void Item_cache_row::illegal_method_call(const char *method)
{
  DBUG_ENTER("Item_cache_row::illegal_method_call");
  DBUG_PRINT("error", ("!!! %s method was called for row item", method));
  DBUG_ASSERT(0);
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  my_error(ER_OPERAND_COLUMNS, MYF(0), 1);
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  DBUG_VOID_RETURN;
}

6404

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bool Item_cache_row::check_cols(uint c)
{
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  if (c != item_count)
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  {
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    my_error(ER_OPERAND_COLUMNS, MYF(0), c);
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    return 1;
  }
  return 0;
}

6415

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bool Item_cache_row::null_inside()
{
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  for (uint i= 0; i < item_count; i++)
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  {
    if (values[i]->cols() > 1)
    {
      if (values[i]->null_inside())
	return 1;
    }
    else
    {
6427
      values[i]->update_null_value();
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      if (values[i]->null_value)
	return 1;
    }
  }
  return 0;
}

6435

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void Item_cache_row::bring_value()
{
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  for (uint i= 0; i < item_count; i++)
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    values[i]->bring_value();
  return;
}
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6443

6444 6445
Item_type_holder::Item_type_holder(THD *thd, Item *item)
  :Item(thd, item), enum_set_typelib(0), fld_type(get_real_type(item))
6446 6447
{
  DBUG_ASSERT(item->fixed);
6448
  maybe_null= item->maybe_null;
6449
  collation.set(item->collation);
6450
  get_full_info(item);
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  /* fix variable decimals which always is NOT_FIXED_DEC */
  if (Field::result_merge_type(fld_type) == INT_RESULT)
    decimals= 0;
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  prev_decimal_int_part= item->decimal_int_part();
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}


6458
/*
6459
  Return expression type of Item_type_holder
6460 6461

  SYNOPSIS
6462
    Item_type_holder::result_type()
6463 6464

  RETURN
6465
     Item_result (type of internal MySQL expression result)
6466 6467
*/

6468
Item_result Item_type_holder::result_type() const
6469
{
6470
  return Field::result_merge_type(fld_type);
6471
}
6472

6473

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/*
6475
  Find real field type of item
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  SYNOPSIS
6478
    Item_type_holder::get_real_type()
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  RETURN
6481
    type of field which should be created to store item value
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*/

6484
enum_field_types Item_type_holder::get_real_type(Item *item)
6485
{
6486
  switch(item->type())
6487
  {
6488
  case FIELD_ITEM:
6489
  {
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    /*
6491 6492
      Item_fields::field_type ask Field_type() but sometimes field return
      a different type, like for enum/set, so we need to ask real type.
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    */
6494 6495 6496 6497 6498 6499
    Field *field= ((Item_field *) item)->field;
    enum_field_types type= field->real_type();
    /* work around about varchar type field detection */
    if (type == MYSQL_TYPE_STRING && field->type() == MYSQL_TYPE_VAR_STRING)
      return MYSQL_TYPE_VAR_STRING;
    return type;
6500
  }
6501
  case SUM_FUNC_ITEM:
6502
  {
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    /*
      Argument of aggregate function sometimes should be asked about field
      type
    */
6507 6508
    Item_sum *item_sum= (Item_sum *) item;
    if (item_sum->keep_field_type())
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      return get_real_type(item_sum->args[0]);
    break;
  }
  case FUNC_ITEM:
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    if (((Item_func *) item)->functype() == Item_func::GUSERVAR_FUNC)
6514
    {
6515
      /*
6516 6517 6518 6519
        There are work around of problem with changing variable type on the
        fly and variable always report "string" as field type to get
        acceptable information for client in send_field, so we make field
        type from expression type.
6520
      */
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      switch (item->result_type()) {
6522 6523 6524 6525 6526 6527
      case STRING_RESULT:
        return MYSQL_TYPE_VAR_STRING;
      case INT_RESULT:
        return MYSQL_TYPE_LONGLONG;
      case REAL_RESULT:
        return MYSQL_TYPE_DOUBLE;
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      case DECIMAL_RESULT:
        return MYSQL_TYPE_NEWDECIMAL;
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      case ROW_RESULT:
      default:
        DBUG_ASSERT(0);
        return MYSQL_TYPE_VAR_STRING;
      }
6535
    }
6536 6537 6538
    break;
  default:
    break;
6539
  }
6540
  return item->field_type();
6541 6542
}

6543
/*
6544 6545
  Find field type which can carry current Item_type_holder type and
  type of given Item.
6546 6547

  SYNOPSIS
6548 6549 6550
    Item_type_holder::join_types()
    thd     thread handler
    item    given item to join its parameters with this item ones
6551 6552

  RETURN
6553 6554
    TRUE   error - types are incompatible
    FALSE  OK
6555 6556
*/

6557
bool Item_type_holder::join_types(THD *thd, Item *item)
6558
{
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  uint max_length_orig= max_length;
  uint decimals_orig= decimals;
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  DBUG_ENTER("Item_type_holder::join_types");
  DBUG_PRINT("info:", ("was type %d len %d, dec %d name %s",
                       fld_type, max_length, decimals,
                       (name ? name : "<NULL>")));
  DBUG_PRINT("info:", ("in type %d len %d, dec %d",
                       get_real_type(item),
                       item->max_length, item->decimals));
6568
  fld_type= Field::field_type_merge(fld_type, get_real_type(item));
6569
  {
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    int item_decimals= item->decimals;
    /* fix variable decimals which always is NOT_FIXED_DEC */
    if (Field::result_merge_type(fld_type) == INT_RESULT)
      item_decimals= 0;
    decimals= max(decimals, item_decimals);
6575
  }
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  if (Field::result_merge_type(fld_type) == DECIMAL_RESULT)
6577
  {
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    decimals= min(max(decimals, item->decimals), DECIMAL_MAX_SCALE);
    int precision= min(max(prev_decimal_int_part, item->decimal_int_part())
                       + decimals, DECIMAL_MAX_PRECISION);
    unsigned_flag&= item->unsigned_flag;
    max_length= my_decimal_precision_to_length(precision, decimals,
                                               unsigned_flag);
6584
  }
6585

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  switch (Field::result_merge_type(fld_type))
  {
  case STRING_RESULT:
6589
  {
6590
    const char *old_cs, *old_derivation;
6591
    uint32 old_max_chars= max_length / collation.collation->mbmaxlen;
6592 6593
    old_cs= collation.collation->name;
    old_derivation= collation.derivation_name();
6594
    if (collation.aggregate(item->collation, MY_COLL_ALLOW_CONV))
6595
    {
6596
      my_error(ER_CANT_AGGREGATE_2COLLATIONS, MYF(0),
6597 6598 6599 6600
	       old_cs, old_derivation,
	       item->collation.collation->name,
	       item->collation.derivation_name(),
	       "UNION");
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      DBUG_RETURN(TRUE);
6602
    }
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    /*
      To figure out max_length, we have to take into account possible
      expansion of the size of the values because of character set
      conversions.
     */
    max_length= max(old_max_chars * collation.collation->mbmaxlen,
                    display_length(item) / item->collation.collation->mbmaxlen *
                    collation.collation->mbmaxlen);
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    break;
6612
  }
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  case REAL_RESULT:
  {
    if (decimals != NOT_FIXED_DEC)
    {
      int delta1= max_length_orig - decimals_orig;
      int delta2= item->max_length - item->decimals;
6619 6620 6621 6622 6623 6624 6625 6626 6627 6628 6629
      max_length= max(delta1, delta2) + decimals;
      if (fld_type == MYSQL_TYPE_FLOAT && max_length > FLT_DIG + 2) 
      {
        max_length= FLT_DIG + 6;
        decimals= NOT_FIXED_DEC;
      } 
      if (fld_type == MYSQL_TYPE_DOUBLE && max_length > DBL_DIG + 2) 
      {
        max_length= DBL_DIG + 7;
        decimals= NOT_FIXED_DEC;
      }
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    }
    else
      max_length= (fld_type == MYSQL_TYPE_FLOAT) ? FLT_DIG+6 : DBL_DIG+7;
    break;
6634
  }
6635 6636
  default:
    max_length= max(max_length, display_length(item));
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  };
6638 6639
  maybe_null|= item->maybe_null;
  get_full_info(item);
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  /* Remember decimal integer part to be used in DECIMAL_RESULT handleng */
  prev_decimal_int_part= decimal_int_part();
6643 6644
  DBUG_PRINT("info", ("become type: %d  len: %u  dec: %u",
                      (int) fld_type, max_length, (uint) decimals));
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  DBUG_RETURN(FALSE);
6646 6647
}

6648 6649
/*
  Calculate lenth for merging result for given Item type
6650

6651 6652 6653
  SYNOPSIS
    Item_type_holder::real_length()
    item  Item for lrngth detection
6654

6655 6656 6657
  RETURN
    length
*/
6658

6659
uint32 Item_type_holder::display_length(Item *item)
6660 6661
{
  if (item->type() == Item::FIELD_ITEM)
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    return ((Item_field *)item)->max_disp_length();
6663

6664
  switch (item->field_type())
6665
  {
6666 6667 6668 6669 6670 6671 6672
  case MYSQL_TYPE_DECIMAL:
  case MYSQL_TYPE_TIMESTAMP:
  case MYSQL_TYPE_DATE:
  case MYSQL_TYPE_TIME:
  case MYSQL_TYPE_DATETIME:
  case MYSQL_TYPE_YEAR:
  case MYSQL_TYPE_NEWDATE:
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  case MYSQL_TYPE_VARCHAR:
  case MYSQL_TYPE_BIT:
  case MYSQL_TYPE_NEWDECIMAL:
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  case MYSQL_TYPE_ENUM:
  case MYSQL_TYPE_SET:
  case MYSQL_TYPE_TINY_BLOB:
  case MYSQL_TYPE_MEDIUM_BLOB:
  case MYSQL_TYPE_LONG_BLOB:
  case MYSQL_TYPE_BLOB:
  case MYSQL_TYPE_VAR_STRING:
  case MYSQL_TYPE_STRING:
  case MYSQL_TYPE_GEOMETRY:
6685
    return item->max_length;
6686 6687 6688 6689 6690
  case MYSQL_TYPE_TINY:
    return 4;
  case MYSQL_TYPE_SHORT:
    return 6;
  case MYSQL_TYPE_LONG:
6691
    return MY_INT32_NUM_DECIMAL_DIGITS;
6692 6693 6694
  case MYSQL_TYPE_FLOAT:
    return 25;
  case MYSQL_TYPE_DOUBLE:
6695
    return 53;
6696
  case MYSQL_TYPE_NULL:
6697
    return 0;
6698
  case MYSQL_TYPE_LONGLONG:
6699
    return 20;
6700 6701
  case MYSQL_TYPE_INT24:
    return 8;
6702 6703 6704 6705 6706
  default:
    DBUG_ASSERT(0); // we should never go there
    return 0;
  }
}
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/*
  Make temporary table field according collected information about type
  of UNION result

  SYNOPSIS
    Item_type_holder::make_field_by_type()
    table  temporary table for which we create fields

  RETURN
    created field
*/

Field *Item_type_holder::make_field_by_type(TABLE *table)
{
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  /*
    The field functions defines a field to be not null if null_ptr is not 0
  */
  uchar *null_ptr= maybe_null ? (uchar*) "" : 0;
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  Field *field;

  switch (fld_type) {
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  case MYSQL_TYPE_ENUM:
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    DBUG_ASSERT(enum_set_typelib);
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    field= new Field_enum((char *) 0, max_length, null_ptr, 0,
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                          Field::NONE, name,
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                          get_enum_pack_length(enum_set_typelib->count),
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                          enum_set_typelib, collation.collation);
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    if (field)
      field->init(table);
    return field;
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  case MYSQL_TYPE_SET:
    DBUG_ASSERT(enum_set_typelib);
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    field= new Field_set((char *) 0, max_length, null_ptr, 0,
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                         Field::NONE, name,
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                         get_set_pack_length(enum_set_typelib->count),
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                         enum_set_typelib, collation.collation);
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    if (field)
      field->init(table);
    return field;
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  default:
    break;
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  }
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  return tmp_table_field_from_field_type(table, 0);
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}


/*
  Get full information from Item about enum/set fields to be able to create
  them later

  SYNOPSIS
    Item_type_holder::get_full_info
    item    Item for information collection
*/
void Item_type_holder::get_full_info(Item *item)
{
  if (fld_type == MYSQL_TYPE_ENUM ||
      fld_type == MYSQL_TYPE_SET)
  {
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    if (item->type() == Item::SUM_FUNC_ITEM &&
        (((Item_sum*)item)->sum_func() == Item_sum::MAX_FUNC ||
         ((Item_sum*)item)->sum_func() == Item_sum::MIN_FUNC))
      item = ((Item_sum*)item)->args[0];
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    /*
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      We can have enum/set type after merging only if we have one enum|set
      field (or MIN|MAX(enum|set field)) and number of NULL fields
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    */
    DBUG_ASSERT((enum_set_typelib &&
                 get_real_type(item) == MYSQL_TYPE_NULL) ||
                (!enum_set_typelib &&
                 item->type() == Item::FIELD_ITEM &&
                 (get_real_type(item) == MYSQL_TYPE_ENUM ||
                  get_real_type(item) == MYSQL_TYPE_SET) &&
                 ((Field_enum*)((Item_field *) item)->field)->typelib));
    if (!enum_set_typelib)
    {
      enum_set_typelib= ((Field_enum*)((Item_field *) item)->field)->typelib;
    }
  }
}


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double Item_type_holder::val_real()
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{
  DBUG_ASSERT(0); // should never be called
  return 0.0;
}


longlong Item_type_holder::val_int()
{
  DBUG_ASSERT(0); // should never be called
  return 0;
}

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my_decimal *Item_type_holder::val_decimal(my_decimal *)
{
  DBUG_ASSERT(0); // should never be called
  return 0;
}
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String *Item_type_holder::val_str(String*)
{
  DBUG_ASSERT(0); // should never be called
  return 0;
}

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void Item_result_field::cleanup()
{
  DBUG_ENTER("Item_result_field::cleanup()");
  Item::cleanup();
  result_field= 0;
  DBUG_VOID_RETURN;
}

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/*
  Dummy error processor used by default by Name_resolution_context

  SYNOPSIS
    dummy_error_processor()

  NOTE
    do nothing
*/

void dummy_error_processor(THD *thd, void *data)
{}

/*
  Wrapper of hide_view_error call for Name_resolution_context error processor

  SYNOPSIS
    view_error_processor()

  NOTE
    hide view underlying tables details in error messages
*/

void view_error_processor(THD *thd, void *data)
{
  ((TABLE_LIST *)data)->hide_view_error(thd);
}

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/*****************************************************************************
** Instantiate templates
*****************************************************************************/

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#ifdef HAVE_EXPLICIT_TEMPLATE_INSTANTIATION
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template class List<Item>;
template class List_iterator<Item>;
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template class List_iterator_fast<Item>;
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template class List_iterator_fast<Item_field>;
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template class List<List_item>;
#endif