item.cc 152 KB
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/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult 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
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
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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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static void mark_as_dependent(THD *thd,
			      SELECT_LEX *last, SELECT_LEX *current,
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			      Item_ident *item);

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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
{
  to->set(val->real, decimals, &my_charset_bin);
  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;
  item->max_length= 21;
  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 */
  str->set(nr,decimals, &my_charset_bin);
  return str;
}


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


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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void *Item::operator new(size_t size, Item *reuse, uint *rsize)
{
  if (reuse && size <= reuse->rsize)
  {
    if (rsize)
      (*rsize)= reuse->rsize;
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    reuse->cleanup();
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    delete reuse;
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    TRASH((void *)reuse, size);
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    return (void *)reuse;
  }
  if (rsize)
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    (*rsize)= (uint) size;
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  return (void *)sql_alloc((uint)size);
}


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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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  /* 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)
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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;
    str->append(" AS ", 4);
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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");
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  DBUG_PRINT("info", ("Item: 0x%lx, Type: %d, name %s, original name %s",
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		      this, (int)type(), name ? name : "(null)",
                      orig_name ? orig_name : "null"));
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  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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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
          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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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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    /*
      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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  }
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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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    Allow conversion from and to "binary".
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    Don't allow automatic conversion to non-Unicode charsets,
    as it potentially loses data.
  */
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  if (collation.collation != &my_charset_bin &&
      tocs != &my_charset_bin &&
      !(tocs->state & MY_CS_UNICODE))
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    return NULL; // safe conversion is not possible
  return new Item_func_conv_charset(this, tocs);
}


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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_int_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;
}


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


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


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


String *Item_splocal::val_str(String *sp)
{
  DBUG_ASSERT(fixed);
  Item *it= this_item();
  String *ret= it->val_str(sp);
  Item::null_value= it->null_value;
  return ret;
}


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


bool Item_splocal::is_null()
{
  Item *it= this_item();
  bool ret= it->is_null();
  Item::null_value= it->null_value;
  return ret;
}


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Item *
Item_splocal::this_item()
{
  THD *thd= current_thd;

  return thd->spcont->get_item(m_offset);
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}

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Item **
Item_splocal::this_item_addr(THD *thd, Item **addr)
{
  return thd->spcont->get_item_addr(m_offset);
}

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Item *
Item_splocal::this_const_item() const
{
  THD *thd= current_thd;

  return thd->spcont->get_item(m_offset);
}

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Item::Type
Item_splocal::type() const
{
  THD *thd= current_thd;

  if (thd->spcont)
    return thd->spcont->get_item(m_offset)->type();
  return NULL_ITEM;		// Anything but SUBSELECT_ITEM
}


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bool Item_splocal::fix_fields(THD *, Item **)
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{
  Item *it= this_item();
  DBUG_ASSERT(it->fixed);
  max_length= it->max_length;
  decimals= it->decimals;
  fixed= 1;
  return FALSE;
}


void Item_splocal::cleanup()
{
  fixed= 0;
}


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


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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

  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,
                           List<Item> &fields, Item **ref)
{
  if (type() != SUM_FUNC_ITEM && with_sum_func)
  {
    /* Will split complicated items and ignore simple ones */
    split_sum_func(thd, ref_pointer_array, fields);
  }
  else if ((type() == SUM_FUNC_ITEM ||
            (used_tables() & ~PARAM_TABLE_BIT)) &&
           type() != REF_ITEM)
  {
    /*
      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)
    */
    uint el= fields.elements;
    Item *new_item;    
    ref_pointer_array[el]= this;
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    if (!(new_item= new Item_ref(&thd->lex->current_select->context,
                                 ref_pointer_array + el, 0, name)))
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      return;                                   // fatal_error is set
    fields.push_front(this);
    ref_pointer_array[el]= this;
    thd->change_item_tree(ref, new_item);
  }
}


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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
void my_coll_agg_error(Item** args, uint count, const char *fname)
{
  if (count == 2)
    my_coll_agg_error(args[0]->collation, args[1]->collation, fname);
  else if (count == 3)
    my_coll_agg_error(args[0]->collation, args[1]->collation,
                      args[2]->collation, fname);
  else
    my_error(ER_CANT_AGGREGATE_NCOLLATIONS,MYF(0),fname);
}


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


/* 
  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)
*/

bool agg_item_charsets(DTCollation &coll, const char *fname,
                       Item **args, uint nargs, uint flags)
{
  Item **arg, **last, *safe_args[2];
  if (agg_item_collations(coll, fname, args, nargs, flags))
    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.
  */
  if (nargs >=2 && nargs <= 3)
  {
    safe_args[0]= args[0];
    safe_args[1]= args[1];
  }

  THD *thd= current_thd;
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  Query_arena *arena, backup;
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  bool res= FALSE;
  /*
    In case we're in statement prepare, create conversion item
    in its memory: it will be reused on each execute.
  */
  arena= thd->change_arena_if_needed(&backup);

  for (arg= args, last= args + nargs; arg < last; arg++)
  {
    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];
        args[1]= safe_args[1];
      }
      my_coll_agg_error(args, nargs, fname);
      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.
    */
    if (arena)
      *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)
    thd->restore_backup_item_arena(arena, &backup);
  return res;
}




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

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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)
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{
  set_field(f);
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  /*
    field_name and talbe_name should not point to garbage
    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)
  :Item_ident(context_arg, f->table->s->db, *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)
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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->current_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),
   have_privileges(0), any_privileges(0)
{
  collation.set(DERIVATION_IMPLICIT);
}

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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),
   any_privileges(item->any_privileges)
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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_length();
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  table_name= *field_par->table_name;
  field_name= field_par->field_name;
  db_name= field_par->table->s->db;
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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(), DERIVATION_IMPLICIT);
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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)
  {
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    const char *nm= field_name ? 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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    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;
  if (item_field->field)
    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) &&
	  (!item_field->table_name ||
	   (!my_strcasecmp(table_alias_charset, item_field->table_name,
			   table_name) &&
	    (!item_field->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,
                                             decimals, !decimal_value.sign());
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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,
                                             !decimal_value.sign());
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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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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(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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inline bool check_if_only_end_space(CHARSET_INFO *cs, char *str, char *end)
{
  return str+ cs->cset->scan(cs, str, end, MY_SEQ_SPACES) == end;
}


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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}
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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 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;
  value.time.time_type= type;
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  if (value.time.year > 9999 || value.time.month > 12 ||
      value.time.day > 31 ||
      type != MYSQL_TIMESTAMP_TIME && value.time.hour > 23 ||
      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, 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:
      set_int(*(longlong*)entry->value, 21);
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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= 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:
    return field->store(value.integer);
  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));
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  case NULL_VALUE:
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    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:
    return (longlong) (value.real + (value.real > 0 ? 0.5 : -0.5));
  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:
2340
    DBUG_ASSERT(0);
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  }
2342
  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;
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  case REAL_VALUE:
    str->set(value.real, NOT_FIXED_DEC, &my_charset_bin);
    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:
  {
2395
    if (str->reserve(MAX_DATE_STRING_REP_LENGTH))
2396
      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
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  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
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{
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  switch (state) {
  case INT_VALUE:
    str->set(value.integer, &my_charset_bin);
    break;
  case REAL_VALUE:
    str->set(value.real, NOT_FIXED_DEC, &my_charset_bin);
    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:
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    {
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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 
      */
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      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;
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    }
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  case STRING_VALUE:
  case LONG_DATA_VALUE:
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    {
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      char *buf, *ptr;
      str->length(0);
      if (str->reserve(str_value.length()*2+3))
        break;

      buf= str->c_ptr_quick();
      ptr= buf;
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      if (value.cs_info.character_set_client->escape_with_backslash_is_dangerous)
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      {
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        ptr= str_to_hex(ptr, str_value.ptr(), str_value.length());
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      }
      else
      {
        *ptr++= '\'';
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        ptr+= escape_string_for_mysql(str_value.charset(), ptr, 0,
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                                      str_value.ptr(), str_value.length());
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        *ptr++='\'';
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      }
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      str->length((uint32) (ptr - buf));
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      break;
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    }
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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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Item *
Item_param::new_item()
{
  /* 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));
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  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:
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    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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/*
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  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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}

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double Item_ref_null_helper::val_real()
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{
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  DBUG_ASSERT(fixed == 1);
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  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()
{
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  DBUG_ASSERT(fixed == 1);
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  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);
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  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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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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/*
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  Mark item and SELECT_LEXs as dependent if item was resolved in outer SELECT
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  SYNOPSIS
    mark_as_dependent()
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    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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*/

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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;
  Item_field *cur_field;
  int         cur_match_degree= 0;

  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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  DBUG_ASSERT(field_name != 0);
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  for (ORDER *cur_group= group_list ; cur_group ; cur_group= cur_group->next)
  {
    if ((*(cur_group->item))->type() == Item::FIELD_ITEM)
    {
      cur_field= (Item_field*) *cur_group->item;
      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
    derived SELECT column.

  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,
      - otherwise return the found SELECT column.


  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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  bool not_used;
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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,
                                      &not_used)))
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    return NULL; /* Some error occurred. */

  /* 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);

    }
  }

  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 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
          {
            if - 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
            {
              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.
          }
        }
      }

    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
*/

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bool Item_field::fix_fields(THD *thd, Item **reference)
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{
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  enum_parsing_place place= NO_MATTER;
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  DBUG_ASSERT(fixed == 0);
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  if (!field)					// If field is not checked
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  {
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    bool upward_lookup= FALSE;
    Field *from_field= (Field *)not_found_field;
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    /*
      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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    if ((from_field= find_field_in_tables(thd, this,
                                          context->first_name_resolution_table,
                                          context->last_name_resolution_table,
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                                          reference,
                                          IGNORE_EXCEPT_NON_UNIQUE,
                                          !any_privileges &&
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                                          context->check_privileges,
                                          TRUE)) ==
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	not_found_field)
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    {
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      /*
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        If there are outer contexts (outer selects, but current select is
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        not derived table or view) try to resolve this reference in the
        outer contexts.

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        We treat each subselect as a separate namespace, so that different
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        subselects may contain columns with the same names. The subselects
        are searched starting from the innermost.
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      */
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      Name_resolution_context *last_checked_context= context;
      Item **ref= (Item **) not_found_item;
      Name_resolution_context *outer_context= context->outer_context;
      for (;
           outer_context;
           outer_context= outer_context->outer_context)
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      {
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        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;
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        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).
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          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 ((place != IN_HAVING ||
             (!select->with_sum_func &&
              select->group_list.elements == 0)) &&
            (from_field= find_field_in_tables(thd, this,
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                                              outer_context->
                                                first_name_resolution_table,
                                              outer_context->
                                                last_name_resolution_table,
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                                              reference,
                                              IGNORE_EXCEPT_NON_UNIQUE,
                                              outer_context->
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                                              check_privileges,
                                              TRUE)) !=
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            not_found_field)
        {
          if (from_field)
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          {
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            if (from_field != view_ref_found)
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            {
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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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            }
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            else
            {
              Item::Type type= (*reference)->type();
              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,
                                ((type == REF_ITEM || type == FIELD_ITEM) ?
                                 (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 FALSE;
            }
          }
          break;
        }
3169

3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182
        /* 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)))
            goto error; /* 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;
          }
        }
3183

3184 3185 3186 3187 3188 3189 3190
        /*
          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;
3191
      }
3192

3193
      DBUG_ASSERT(ref != 0);
3194
      if (!from_field)
3195
	goto error;
3196
      if (ref == not_found_item && from_field == not_found_field)
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3197
      {
3198
	if (upward_lookup)
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3199
	{
3200
          // We can't say exactly what absent table or field
3201
	  my_error(ER_BAD_FIELD_ERROR, MYF(0), full_name(), thd->where);
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3202
	}
3203
	else
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3204
	{
3205
          /* Call find_field_in_tables only to report the error */
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3206 3207 3208
	  find_field_in_tables(thd, this,
                               context->first_name_resolution_table,
                               context->last_name_resolution_table,
3209 3210
                               reference, REPORT_ALL_ERRORS,
                               !any_privileges &&
3211
                               context->check_privileges, TRUE);
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3212
	}
3213
	goto error;
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3214
      }
3215
      else if (ref != not_found_item)
3216
      {
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3217 3218 3219
        Item *save;
        Item_ref *rf;

3220
        /* Should have been checked in resolve_ref_in_select_and_group(). */
3221
        DBUG_ASSERT(*ref && (*ref)->fixed);
3222 3223
        /*
          Here, a subset of actions performed by Item_ref::set_properties
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3224 3225 3226
          is not enough. So we pass ptr to NULL into Item_[direct]_ref
          constructor, so no initialization is performed, and call 
          fix_fields() below.
3227
        */
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3228 3229 3230
        save= *ref;
        *ref= NULL;                             // Don't call set_properties()
        rf= (place == IN_HAVING ?
3231 3232 3233 3234
             new Item_ref(context, ref, (char*) table_name,
                          (char*) field_name) :
             new Item_direct_ref(context, ref, (char*) table_name,
                                 (char*) field_name));
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3235
        *ref= save;
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3236
	if (!rf)
3237
	  goto error;
3238
        thd->change_item_tree(reference, rf);
3239 3240 3241 3242
	/*
	  rf is Item_ref => never substitute other items (in this case)
	  during fix_fields() => we can use rf after fix_fields()
	*/
3243
        DBUG_ASSERT(!rf->fixed);                // Assured by Item_ref()
3244 3245
        if (rf->fix_fields(thd, reference) || rf->check_cols(1))
	  goto error;
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3246

3247 3248 3249
	mark_as_dependent(thd, last_checked_context->select_lex,
                          context->select_lex, this,
                          rf);
3250
	return FALSE;
3251
      }
3252
      else
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3253
      {
3254 3255 3256 3257
	mark_as_dependent(thd, last_checked_context->select_lex,
                          context->select_lex,
                          this, this);
	if (last_checked_context->select_lex->having_fix_field)
3258 3259
	{
	  Item_ref *rf;
3260 3261
          rf= new Item_ref(context,
                           (cached_table->db[0] ? cached_table->db : 0),
3262
                           (char*) cached_table->alias, (char*) field_name);
3263
	  if (!rf)
3264
	    goto error;
3265
          thd->change_item_tree(reference, rf);
3266 3267 3268 3269
	  /*
	    rf is Item_ref => never substitute other items (in this case)
	    during fix_fields() => we can use rf after fix_fields()
	  */
3270
          DBUG_ASSERT(!rf->fixed);                // Assured by Item_ref()
3271 3272 3273
          if (rf->fix_fields(thd, reference) || rf->check_cols(1))
            goto error;
          return FALSE;
3274
	}
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3275
      }
3276
    }
3277
    else if (!from_field)
3278
      goto error;
3279

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VIEW  
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3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291
    /*
      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
      (i.e. do not register this substitution for reverting on cleupup()
      (register_item_tree_changing())), because this subtree will be
      fix_field'ed during setup_tables()->setup_ancestor() (i.e. before
      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.
    */
3292 3293 3294 3295
    if (from_field == view_ref_found)
      return FALSE;

    set_field(from_field);
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3296
  }
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3297
  else if (thd->set_query_id && field->query_id != thd->query_id)
3298 3299 3300 3301 3302
  {
    /* We only come here in unions */
    TABLE *table=field->table;
    field->query_id=thd->query_id;
    table->used_fields++;
3303
    table->used_keys.intersect(field->part_of_key);
3304
  }
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VIEW  
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3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316
#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;
3317
      tab= cached_table->table_name;
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VIEW  
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3318 3319 3320 3321 3322
    }
    if (!(have_privileges= (get_column_grant(thd, &field->table->grant,
                                             db, tab, field_name) &
                            VIEW_ANY_ACL)))
    {
3323 3324 3325
      my_error(ER_COLUMNACCESS_DENIED_ERROR, MYF(0),
               "ANY", thd->priv_user, thd->host_or_ip,
               field_name, tab);
3326
      goto error;
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VIEW  
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3327 3328 3329
    }
  }
#endif
3330
  fixed= 1;
3331
  return FALSE;
3332 3333 3334 3335

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

3338 3339 3340 3341 3342 3343 3344 3345

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


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3346 3347
void Item_field::cleanup()
{
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  DBUG_ENTER("Item_field::cleanup");
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3349
  Item_ident::cleanup();
3350 3351
  /*
    Even if this object was created by direct link to field in setup_wild()
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3352
    it will be linked correctly next time by name of field and table alias.
3353 3354
    I.e. we can drop 'field'.
   */
3355
  field= result_field= 0;
3356
  DBUG_VOID_RETURN;
3357
}
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3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378

/*
  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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3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400
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;
}


/*
3401 3402
  Set a pointer to the multiple equality the field reference belongs to
  (if any)
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3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424
   
  SYNOPSIS
    equal_fields_propagator()
    arg - reference to list of multiple equalities where
          the field (this object) is to be looked for
  
  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
    of the transform method.  

  RETURN VALUES
    pointer to the replacing constant item, if the field item was substituted 
    pointer to the field item, otherwise.
*/
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3425

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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();
  if (!item)
    item= this;
  return item;
}


/*
3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453
  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
*/

Item *Item_field::set_no_const_sub(byte *arg)
{
  if (field->charset() != &my_charset_bin)
    no_const_subst=1;
  return this;
}


/*
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3454
  Replace an Item_field for an equal Item_field that evaluated earlier
3455
  (if any)
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3456 3457
   
  SYNOPSIS
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3458
    replace_equal_field_()
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    arg - a dummy parameter, is not used here
  
  DESCRIPTION
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3462 3463 3464 3465 3466
    The function returns a pointer to an item that is taken from
    the very beginning of the item_equal list which the Item_field
    object refers to (belongs to).  
    If the Item_field object does not refer any Item_equal object
    'this' is returned 
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3467 3468 3469

  NOTES
    This function is supposed to be called as a callback parameter in calls
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3470
    of the thransformer method.  
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3471 3472

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

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Item *Item_field::replace_equal_field(byte *arg)
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3478 3479 3480 3481 3482
{
  if (item_equal)
  {
    Item_field *subst= item_equal->get_first();
    if (!field->eq(subst->field))
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      return subst;
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  }
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  return this;
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}
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3487

3488

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3489 3490
void Item::init_make_field(Send_field *tmp_field,
			   enum enum_field_types field_type)
3491
{
3492
  char *empty_name= (char*) "";
3493
  tmp_field->db_name=		empty_name;
3494 3495 3496 3497
  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;
3498
  tmp_field->charsetnr=         collation.collation->number;
3499 3500 3501
  tmp_field->flags=             (maybe_null ? 0 : NOT_NULL_FLAG) | 
                                (my_binary_compare(collation.collation) ?
                                 BINARY_FLAG : 0);
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3502 3503 3504
  tmp_field->type=field_type;
  tmp_field->length=max_length;
  tmp_field->decimals=decimals;
3505 3506
  if (unsigned_flag)
    tmp_field->flags |= UNSIGNED_FLAG;
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3507 3508
}

3509
void Item::make_field(Send_field *tmp_field)
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3510
{
3511
  init_make_field(tmp_field, field_type());
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3512 3513 3514
}


3515 3516
void Item_empty_string::make_field(Send_field *tmp_field)
{
3517 3518 3519 3520 3521
  enum_field_types type= FIELD_TYPE_VAR_STRING;
  if (max_length >= 16777216)
    type= FIELD_TYPE_LONG_BLOB;
  else if (max_length >= 65536)
    type= FIELD_TYPE_MEDIUM_BLOB;
3522
  init_make_field(tmp_field, type);
3523 3524
}

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3526
enum_field_types Item::field_type() const
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{
3528
  switch (result_type()) {
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3529 3530 3531 3532 3533 3534 3535
  case STRING_RESULT:  return MYSQL_TYPE_VARCHAR;
  case INT_RESULT:     return FIELD_TYPE_LONGLONG;
  case DECIMAL_RESULT: return FIELD_TYPE_NEWDECIMAL;
  case REAL_RESULT:    return FIELD_TYPE_DOUBLE;
  case ROW_RESULT:
  default:
    DBUG_ASSERT(0);
3536 3537
    return MYSQL_TYPE_VARCHAR;
  }
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3538 3539
}

3540

3541 3542 3543 3544 3545 3546 3547 3548 3549 3550 3551 3552 3553 3554 3555 3556 3557 3558 3559 3560 3561 3562 3563 3564 3565 3566 3567
/*
  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)
{
  if (max_length > CONVERT_IF_BIGGER_TO_BLOB)
    return new Field_blob(max_length, maybe_null, name, table,
                          collation.collation);
  if (max_length > 0)
    return new Field_varstring(max_length, maybe_null, name, table,
                               collation.collation);
  return new Field_string(max_length, maybe_null, name, table,
                          collation.collation);
}


3568 3569 3570 3571 3572 3573 3574 3575 3576 3577 3578
/*
  Create a field based on field_type of argument

  For now, this is only used to create a field for
  IFNULL(x,something)

  RETURN
    0  error
    #  Created field
*/

3579 3580
Field *Item::tmp_table_field_from_field_type(TABLE *table)
{
3581 3582 3583 3584 3585 3586
  /*
    The field functions defines a field to be not null if null_ptr is not 0
  */
  uchar *null_ptr= maybe_null ? (uchar*) "" : 0;

  switch (field_type()) {
3587
  case MYSQL_TYPE_DECIMAL:
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  case MYSQL_TYPE_NEWDECIMAL:
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    return new Field_new_decimal((char*) 0, max_length, null_ptr, 0,
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3590 3591
                                 Field::NONE, name, table, decimals, 0,
                                 unsigned_flag);
3592
  case MYSQL_TYPE_TINY:
3593 3594
    return new Field_tiny((char*) 0, max_length, null_ptr, 0, Field::NONE,
			  name, table, 0, unsigned_flag);
3595
  case MYSQL_TYPE_SHORT:
3596 3597
    return new Field_short((char*) 0, max_length, null_ptr, 0, Field::NONE,
			   name, table, 0, unsigned_flag);
3598
  case MYSQL_TYPE_LONG:
3599 3600
    return new Field_long((char*) 0, max_length, null_ptr, 0, Field::NONE,
			  name, table, 0, unsigned_flag);
3601 3602
#ifdef HAVE_LONG_LONG
  case MYSQL_TYPE_LONGLONG:
3603 3604
    return new Field_longlong((char*) 0, max_length, null_ptr, 0, Field::NONE,
			      name, table, 0, unsigned_flag);
3605
#endif
3606 3607 3608 3609 3610 3611 3612 3613 3614
  case MYSQL_TYPE_FLOAT:
    return new Field_float((char*) 0, max_length, null_ptr, 0, Field::NONE,
			   name, table, decimals, 0, unsigned_flag);
  case MYSQL_TYPE_DOUBLE:
    return new Field_double((char*) 0, max_length, null_ptr, 0, Field::NONE,
			    name, table, decimals, 0, unsigned_flag);
  case MYSQL_TYPE_NULL:
    return new Field_null((char*) 0, max_length, Field::NONE,
			  name, table, &my_charset_bin);
3615
  case MYSQL_TYPE_INT24:
3616 3617
    return new Field_medium((char*) 0, max_length, null_ptr, 0, Field::NONE,
			    name, table, 0, unsigned_flag);
3618
  case MYSQL_TYPE_NEWDATE:
3619 3620 3621 3622 3623 3624 3625 3626
  case MYSQL_TYPE_DATE:
    return new Field_date(maybe_null, name, table, &my_charset_bin);
  case MYSQL_TYPE_TIME:
    return new Field_time(maybe_null, name, table, &my_charset_bin);
  case MYSQL_TYPE_TIMESTAMP:
  case MYSQL_TYPE_DATETIME:
    return new Field_datetime(maybe_null, name, table, &my_charset_bin);
  case MYSQL_TYPE_YEAR:
3627 3628
    return new Field_year((char*) 0, max_length, null_ptr, 0, Field::NONE,
			  name, table);
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  case MYSQL_TYPE_BIT:
    return new Field_bit_as_char(NULL, max_length, null_ptr, 0, NULL, 0,
                                 Field::NONE, name, table);
3632
  default:
3633
    /* This case should never be chosen */
3634 3635
    DBUG_ASSERT(0);
    /* If something goes awfully wrong, it's better to get a string than die */
3636 3637
  case MYSQL_TYPE_ENUM:
  case MYSQL_TYPE_SET:
3638
  case MYSQL_TYPE_STRING:
3639
  case MYSQL_TYPE_VAR_STRING:
3640
  case MYSQL_TYPE_VARCHAR:
3641
    return make_string_field(table);
3642 3643 3644 3645 3646
  case MYSQL_TYPE_TINY_BLOB:
  case MYSQL_TYPE_MEDIUM_BLOB:
  case MYSQL_TYPE_LONG_BLOB:
  case MYSQL_TYPE_BLOB:
  case MYSQL_TYPE_GEOMETRY:
3647 3648
    return new Field_blob(max_length, maybe_null, name, table,
                          collation.collation);
3649
    break;					// Blob handled outside of case
3650 3651 3652
  }
}

3653

3654 3655
/* ARGSUSED */
void Item_field::make_field(Send_field *tmp_field)
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3656
{
3657
  field->make_field(tmp_field);
3658
  DBUG_ASSERT(tmp_field->table_name != 0);
3659 3660
  if (name)
    tmp_field->col_name=name;			// Use user supplied name
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}

3663

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3664
/*
3665
  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;
3673
    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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{
  if (result_field->is_null())
  {
    null_value=1;
3688
    return set_field_to_null_with_conversions(to, no_conversions);
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  }
  else
  {
    to->set_notnull();
    field_conv(to,result_field);
    null_value=0;
  }
  return 0;
}

3699

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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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{
3718
  return set_field_to_null_with_conversions(field, no_conversions);
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}


3722 3723 3724 3725 3726 3727 3728 3729
/*
  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
3731 3732 3733
    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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{
3742
  int error;
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  if (result_type() == STRING_RESULT ||
      result_type() == REAL_RESULT &&
      field->result_type() == STRING_RESULT)
  {
    String *result;
3748
    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)
3753
    {
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      str_value.set_quick(0, 0, cs);
3755
      return set_field_to_null_with_conversions(field, no_conversions);
3756
    }
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    field->set_notnull();
3758
    error=field->store(result->ptr(),result->length(),cs);
3759
    str_value.set_quick(0, 0, cs);
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  }
  else if (result_type() == REAL_RESULT)
  {
3763
    double nr= val_real();
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    if (null_value)
      return set_field_to_null(field);
    field->set_notnull();
3767
    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)
3782
      return set_field_to_null_with_conversions(field, no_conversions);
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    field->set_notnull();
3784
    error=field->store(nr);
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  }
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  return error;
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}

3789

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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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}

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int Item_uint::save_in_field(Field *field, bool no_conversions)
3801
{
3802 3803 3804 3805
  /*
    TODO: To be fixed when wen have a
    field->store(longlong, unsigned_flag) method 
  */
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  return Item_int::save_in_field(field, no_conversions);
3807 3808
}

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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();
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  return field->store(nr);
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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);
}


3827 3828 3829 3830 3831 3832 3833 3834 3835 3836 3837 3838 3839 3840 3841 3842
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;
}


3843 3844
Item *Item_int_with_ref::new_item()
{
3845
  DBUG_ASSERT(ref->const_item());
3846 3847 3848 3849 3850 3851 3852 3853 3854 3855
  /*
    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()
{
3858
  Item_decimal *item= new Item_decimal(value, 1);
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  return item->neg();
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}
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3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885
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;
3894 3895 3896
  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);
3904
    my_error(ER_ILLEGAL_VALUE_FOR_TYPE, MYF(0), "double", (char*) str_arg);
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  }
  presentation= name=(char*) str_arg;
3907
  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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3914
{
3915
  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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}

3922

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void Item_float::print(String *str)
3924 3925 3926 3927 3928 3929 3930 3931 3932 3933 3934 3935 3936
{
  if (presentation)
  {
    str->append(presentation);
    return;
  }
  char buffer[20];
  String num(buffer, sizeof(buffer), &my_charset_bin);
  num.set(value, decimals, &my_charset_bin);
  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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3943
bool Item_float::eq(const Item *arg, bool binary_cmp) const
3944 3945 3946 3947 3948 3949 3950 3951
{
  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;
3952
    return item->val_real() == value;
3953 3954 3955 3956
  }
  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);
}

3965

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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
3983
  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
3991
  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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{
4014
  int error;
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  field->set_notnull();
  if (field->result_type() == STRING_RESULT)
  {
4018
    error=field->store(str_value.ptr(),str_value.length(),collation.collation);
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  }
  else
  {
    longlong nr=val_int();
4023
    error=field->store(nr);
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  }
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  return error;
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}


4029
bool Item_hex_string::eq(const Item *arg, bool binary_cmp) const
4030 4031 4032 4033 4034 4035 4036 4037 4038 4039
{
  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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4042 4043 4044 4045 4046 4047 4048
{
  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();
4049
  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;
}


4092 4093 4094 4095 4096
/*
  Pack data in buffer for sending
*/

bool Item_null::send(Protocol *protocol, String *packet)
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{
4098
  return protocol->store_null();
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}

/*
4102
  This is only called from items that is not of type item_field
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*/

4105
bool Item::send(Protocol *protocol, String *buffer)
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{
4107 4108
  bool result;
  enum_field_types type;
4109
  LINT_INIT(result);                     // Will be set if null_value == 0
4110 4111 4112

  switch ((type=field_type())) {
  default:
4113 4114 4115 4116 4117 4118 4119 4120 4121
  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:
4122 4123
  case MYSQL_TYPE_STRING:
  case MYSQL_TYPE_VAR_STRING:
4124
  case MYSQL_TYPE_VARCHAR:
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  case MYSQL_TYPE_BIT:
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  case MYSQL_TYPE_NEWDECIMAL:
4127 4128 4129
  {
    String *res;
    if ((res=val_str(buffer)))
4130
      result= protocol->store(res->ptr(),res->length(),res->charset());
4131 4132 4133 4134 4135 4136 4137 4138 4139 4140 4141
    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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  case MYSQL_TYPE_YEAR:
4143 4144 4145 4146 4147 4148 4149
  {
    longlong nr;
    nr= val_int();
    if (!null_value)
      result= protocol->store_short(nr);
    break;
  }
4150
  case MYSQL_TYPE_INT24:
4151 4152 4153 4154 4155 4156 4157 4158 4159 4160 4161 4162 4163 4164 4165 4166
  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;
4170
    nr= (float) val_real();
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    if (!null_value)
      result= protocol->store(nr, decimals, buffer);
    break;
  }
4175 4176
  case MYSQL_TYPE_DOUBLE:
  {
4177
    double nr= val_real();
4178 4179 4180 4181 4182 4183
    if (!null_value)
      result= protocol->store(nr, decimals, buffer);
    break;
  }
  case MYSQL_TYPE_DATETIME:
  case MYSQL_TYPE_DATE:
4184
  case MYSQL_TYPE_TIMESTAMP:
4185 4186
  {
    TIME tm;
4187
    get_date(&tm, TIME_FUZZY_DATE);
4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199 4200 4201 4202 4203 4204 4205 4206 4207 4208
    if (!null_value)
    {
      if (type == MYSQL_TYPE_DATE)
	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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}

4211 4212

bool Item_field::send(Protocol *protocol, String *buffer)
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{
4214
  return protocol->store(result_field);
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}

4217

4218 4219 4220 4221 4222
Item_ref::Item_ref(Name_resolution_context *context_arg,
                   Item **item, const char *table_name_arg,
                   const char *field_name_arg)
  :Item_ident(context_arg, NullS, table_name_arg, field_name_arg),
   result_field(0), ref(item)
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4223 4224 4225 4226
{
  /*
    This constructor used to create some internals references over fixed items
  */
4227
  DBUG_ASSERT(ref != 0);
4228
  if (*ref && (*ref)->fixed)
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    set_properties();
}


4233
/*
4234
  Resolve the name of a reference to a column reference.
4235 4236 4237

  SYNOPSIS
    Item_ref::fix_fields()
4238 4239
    thd       [in]      current thread
    reference [in/out]  view column if this item was resolved to a view column
4240 4241

  DESCRIPTION
4242 4243
    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
4244 4245
    used typically for columns in the HAVING clause which are not under
    aggregate functions.
4246 4247

  NOTES
4248 4249
    The name resolution algorithm used is (where [T_j] is an optional table
    name that qualifies the column name):
4250

4251 4252 4253
      resolve_extended([T_j].col_ref_i)
      {
        Search for a column or derived column named col_ref_i [in table T_j]
4254
        in the SELECT and GROUP clauses of Q.
4255

4256 4257
        if such a column is NOT found AND    // Lookup in outer queries.
           there are outer queries
4258 4259 4260
        {
          for each outer query Q_k beginning from the inner-most one
         {
4261 4262 4263 4264 4265 4266 4267 4268
            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
4269 4270 4271 4272 4273 4274 4275
            {
              search for a column or derived column named col_ref_i
              [in table T_j] in the FROM clause of Q_k;
            }
          }
        }
      }
4276 4277

    This procedure treats GROUP BY and SELECT clauses as one namespace for
4278 4279 4280
    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.
4281

4282 4283 4284
  POSTCONDITION
    Item_ref::ref is 0 or points to a valid item

4285 4286 4287 4288
  RETURN
    TRUE  if error
    FALSE on success
*/
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4289

4290
bool Item_ref::fix_fields(THD *thd, Item **reference)
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4291
{
4292
  enum_parsing_place place= NO_MATTER;
4293
  DBUG_ASSERT(fixed == 0);
4294 4295
  SELECT_LEX *current_sel= thd->lex->current_select;

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  if (!ref || ref == not_found_item)
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  {
4298 4299 4300
    if (!(ref= resolve_ref_in_select_and_group(thd, this,
                                               context->select_lex)))
      goto error;             /* Some error occurred (e.g. ambiguous names). */
4301

4302
    if (ref == not_found_item) /* This reference was not resolved. */
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    {
4304 4305
      Name_resolution_context *last_checked_context= context;
      Name_resolution_context *outer_context= context->outer_context;
4306 4307 4308
      Field *from_field;
      ref= 0;

4309
      if (!outer_context)
4310 4311 4312 4313
      {
        /* The current reference cannot be resolved in this query. */
        my_error(ER_BAD_FIELD_ERROR,MYF(0),
                 this->full_name(), current_thd->where);
4314
        goto error;
4315
      }
4316

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      /*
4318 4319 4320
        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).
4321

4322 4323 4324
        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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      */
4326 4327
      from_field= (Field*) not_found_field;

4328
      do
4329
      {
4330 4331 4332 4333
        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;
4334

4335
        /* Search in the SELECT and GROUP lists of the outer select. */
4336
        if (outer_context->resolve_in_select_list)
4337
        {
4338 4339
          if (!(ref= resolve_ref_in_select_and_group(thd, this, select)))
            goto error; /* Some error occurred (e.g. ambiguous names). */
4340
          if (ref != not_found_item)
4341
          {
4342 4343 4344 4345
            DBUG_ASSERT(*ref && (*ref)->fixed);
            prev_subselect_item->used_tables_cache|= (*ref)->used_tables();
            prev_subselect_item->const_item_cache&= (*ref)->const_item();
            break;
4346 4347
          }
          /*
4348 4349 4350
            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.
4351
          */
4352
          ref= 0;
4353
        }
4354

4355 4356 4357 4358 4359
        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).
4360
          TODO:
4361 4362 4363 4364 4365 4366
          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 ||
4367 4368
             (!select->with_sum_func &&
              select->group_list.elements == 0)))
4369
        {
4370
          /*
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            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
4374
          */
4375
          from_field= find_field_in_tables(thd, this,
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                                           outer_context->
                                             first_name_resolution_table,
                                           outer_context->
                                             last_name_resolution_table,
4380 4381
                                           reference,
                                           IGNORE_EXCEPT_NON_UNIQUE,
4382 4383
                                           outer_context->check_privileges,
                                           TRUE);
4384
          if (! from_field)
4385
            goto error;
4386
          if (from_field == view_ref_found)
4387
          {
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            Item::Type type= (*reference)->type();
            prev_subselect_item->used_tables_cache|=
              (*reference)->used_tables();
            prev_subselect_item->const_item_cache&=
              (*reference)->const_item();
            DBUG_ASSERT((*reference)->type() == REF_ITEM);
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            mark_as_dependent(thd, last_checked_context->select_lex,
                              context->select_lex, this,
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                              ((type == REF_ITEM || type == FIELD_ITEM) ?
                               (Item_ident*) (*reference) :
                               0));
            /*
              view reference found, we substituted it instead of this
              Item, so can quit
            */
4403 4404
            return FALSE;
          }
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          if (from_field != not_found_field)
          {
            prev_subselect_item->used_tables_cache|= from_field->table->map;
            prev_subselect_item->const_item_cache= 0;
            break;
          }
4411
        }
4412 4413 4414 4415 4416 4417
        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;

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        outer_context= outer_context->outer_context;
      } while (outer_context);
4420 4421 4422

      DBUG_ASSERT(from_field != 0 && from_field != view_ref_found);
      if (from_field != not_found_field)
4423
      {
4424 4425
        Item_field* fld;
        if (!(fld= new Item_field(from_field)))
4426
          goto error;
4427
        thd->change_item_tree(reference, fld);
4428 4429
        mark_as_dependent(thd, last_checked_context->select_lex,
                          thd->lex->current_select, this, fld);
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        return FALSE;
      }
      if (ref == 0)
      {
        /* The item was not a table field and not a reference */
        my_error(ER_BAD_FIELD_ERROR, MYF(0),
4436
                 this->full_name(), current_thd->where);
4437
        goto error;
4438
      }
4439 4440
      /* Should be checked in resolve_ref_in_select_and_group(). */
      DBUG_ASSERT(*ref && (*ref)->fixed);
4441 4442
      mark_as_dependent(thd, last_checked_context->select_lex,
                        context->select_lex, this, this);
4443
    }
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4444
  }
4445

4446
  DBUG_ASSERT(*ref);
4447
  /*
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    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.
4451
  */
4452
  if (((*ref)->with_sum_func && name &&
4453
       (depended_from ||
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	!(current_sel->linkage != GLOBAL_OPTIONS_TYPE &&
          current_sel->having_fix_field))) ||
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      !(*ref)->fixed)
  {
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    my_error(ER_ILLEGAL_REFERENCE, MYF(0),
             name, ((*ref)->with_sum_func?
                    "reference to group function":
                    "forward reference in item list"));
4462
    goto error;
4463
  }
4464 4465 4466

  set_properties();

4467
  if ((*ref)->check_cols(1))
4468
    goto error;
4469
  return FALSE;
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error:
  context->process_error(thd);
  return TRUE;
4474 4475
}

4476

4477 4478
void Item_ref::set_properties()
{
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  max_length= (*ref)->max_length;
  maybe_null= (*ref)->maybe_null;
  decimals=   (*ref)->decimals;
4482
  collation.set((*ref)->collation);
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  /*
    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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  with_sum_func= (*ref)->with_sum_func;
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  unsigned_flag= (*ref)->unsigned_flag;
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  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
4493
  fixed= 1;
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}

4496

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void Item_ref::cleanup()
{
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  DBUG_ENTER("Item_ref::cleanup");
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  Item_ident::cleanup();
4501
  result_field= 0;
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  DBUG_VOID_RETURN;
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}


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


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bool Item_ref::send(Protocol *prot, String *tmp)
{
  if (result_field)
    return prot->store(result_field);
  return (*ref)->send(prot, tmp);
}


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double Item_ref::val_result()
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
      return 0.0;
    return result_field->val_real();
  }
4531
  return val_real();
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}


longlong Item_ref::val_int_result()
{
  if (result_field)
  {
    if ((null_value= result_field->is_null()))
4540
      return 0;
4541 4542 4543 4544 4545 4546 4547 4548 4549 4550 4551 4552 4553 4554 4555 4556 4557 4558 4559
    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;
4578
    switch (result_field->result_type()) {
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4579
    case INT_RESULT:
4580
      return result_field->val_int() != 0;
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    case DECIMAL_RESULT:
4582 4583 4584 4585 4586 4587 4588
    {
      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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    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);
  (void) (*ref)->val_int_result();
  return (*ref)->null_value;
}


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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  my_decimal *val= (*ref)->val_decimal_result(decimal_value);
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  null_value= (*ref)->null_value;
  return val;
}

4658 4659 4660
int Item_ref::save_in_field(Field *to, bool no_conversions)
{
  int res;
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  if (result_field)
  {
4663 4664 4665 4666 4667
    if (result_field->is_null())
    {
      null_value= 1;
      return set_field_to_null_with_conversions(to, no_conversions);
    }
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4668 4669 4670
    to->set_notnull();
    field_conv(to, result_field);
    null_value= 0;
4671 4672 4673 4674 4675 4676 4677
    return 0;
  }
  res= (*ref)->save_in_field(to, no_conversions);
  null_value= (*ref)->null_value;
  return res;
}

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4679 4680 4681 4682 4683 4684 4685 4686 4687 4688
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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4689
}
4690 4691


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void Item_ref_null_helper::print(String *str)
{
4694
  str->append("<ref_null_helper>(", 18);
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  if (ref && *ref)
    (*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));
}


4755 4756 4757 4758 4759 4760 4761 4762 4763 4764 4765 4766 4767 4768 4769 4770 4771 4772 4773 4774 4775 4776 4777 4778
/*
  Prepare referenced view viewld then call usual Item_direct_ref::fix_fields

  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);
}

4779 4780 4781 4782 4783 4784 4785 4786 4787 4788 4789 4790 4791 4792 4793 4794 4795 4796 4797 4798 4799 4800 4801 4802 4803 4804 4805 4806 4807
/*
  Compare view field's name with item's name before call to referenced
  item's eq()

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

  DESCRIPTION
    Consider queries:
    create view v1 as select t1.f1 as f2, t1.f2 as f1 from t1;
    select * from v1 order by f1;
    In order to choose right field for sorting we need to compare
    given item's name (f1) to view field's name prior to calling
    referenced item's eq().

  RETURN
    TRUE    Referenced item is equal to given item
    FALSE   otherwise
*/


bool Item_direct_view_ref::eq(const Item *item, bool binary_cmp) const
{
  Item *it= ((Item *) item)->real_item();
  return (!it->name || !my_strcasecmp(system_charset_info, it->name,
          field_name)) && ref && (*ref)->real_item()->eq(it, binary_cmp);
}
4808

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4809 4810
void Item_null_helper::print(String *str)
{
4811
  str->append("<null_helper>(", 14);
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4812 4813 4814 4815 4816
  store->print(str);
  str->append(')');
}


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bool Item_default_value::eq(const Item *item, bool binary_cmp) const
{
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4819
  return item->type() == DEFAULT_VALUE_ITEM && 
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    ((Item_default_value *)item)->arg->eq(arg, binary_cmp);
}

4823

4824
bool Item_default_value::fix_fields(THD *thd, Item **items)
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4825
{
4826
  Item *real_arg;
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  Item_field *field_arg;
  Field *def_field;
4829
  DBUG_ASSERT(fixed == 0);
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4830

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4831
  if (!arg)
4832 4833
  {
    fixed= 1;
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    return FALSE;
4835
  }
4836 4837 4838
  if (!arg->fixed && arg->fix_fields(thd, &arg))
    goto error;

4839

4840 4841
  real_arg= arg->real_item();
  if (real_arg->type() != FIELD_ITEM)
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4842
  {
4843
    my_error(ER_NO_DEFAULT_FOR_FIELD, MYF(0), arg->name);
4844
    goto error;
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4845
  }
4846

4847
  field_arg= (Item_field *)real_arg;
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  if (field_arg->field->flags & NO_DEFAULT_VALUE_FLAG)
  {
4850
    my_error(ER_NO_DEFAULT_FOR_FIELD, MYF(0), field_arg->field->field_name);
4851
    goto error;
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  }
  if (!(def_field= (Field*) sql_alloc(field_arg->field->size_of())))
4854
    goto error;
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4855
  memcpy(def_field, field_arg->field, field_arg->field->size_of());
4856
  def_field->move_field(def_field->table->s->default_values -
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                        def_field->table->record[0]);
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4858
  set_field(def_field);
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  return FALSE;
4860 4861 4862 4863

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

4866

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4867 4868
void Item_default_value::print(String *str)
{
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4869 4870
  if (!arg)
  {
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    str->append("default", 7);
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4872
    return;
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4873
  }
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  str->append("default(", 8);
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  arg->print(str);
  str->append(')');
}
4878

4879 4880 4881 4882 4883 4884 4885

int Item_default_value::save_in_field(Field *field_arg, bool no_conversions)
{
  if (!arg)
  {
    if (field_arg->flags & NO_DEFAULT_VALUE_FLAG)
    {
4886 4887 4888 4889 4890 4891 4892 4893 4894 4895 4896 4897 4898 4899 4900 4901 4902 4903 4904 4905 4906
      if (context->error_processor == &view_error_processor)
      {
        TABLE_LIST *view= (cached_table->belong_to_view ?
                           cached_table->belong_to_view :
                           cached_table);
        // TODO: make correct error message
        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);
}


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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);
}


4923
bool Item_insert_value::fix_fields(THD *thd, Item **items)
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{
4925
  DBUG_ASSERT(fixed == 0);
4926
  if (!arg->fixed && arg->fix_fields(thd, &arg))
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    return TRUE;
4928

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  if (arg->type() == REF_ITEM)
  {
    Item_ref *ref= (Item_ref *)arg;
    if (ref->ref[0]->type() != FIELD_ITEM)
    {
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      return TRUE;
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    }
    arg= ref->ref[0];
  }
  Item_field *field_arg= (Item_field *)arg;
  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());
    def_field->move_field(def_field->table->insert_values -
                          def_field->table->record[0]);
    set_field(def_field);
  }
  else
  {
4951
    Field *tmp_field= field_arg->field;
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    /* charset doesn't matter here, it's to avoid sigsegv only */
4953 4954
    set_field(new Field_null(0, 0, Field::NONE, tmp_field->field_name,
			     tmp_field->table, &my_charset_bin));
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  }
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  return FALSE;
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}

void Item_insert_value::print(String *str)
{
4961
  str->append("values(", 7);
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  arg->print(str);
  str->append(')');
}

4966 4967

/*
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  Find index of Field object which will be appropriate for item
  representing field of row being changed in trigger.
4970 4971 4972 4973 4974 4975 4976 4977

  SYNOPSIS
    setup_field()
      thd   - current thread context
      table - table of trigger (and where we looking for fields)

  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.
4986
*/
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void Item_trigger_field::setup_field(THD *thd, TABLE *table)
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{
  bool save_set_query_id= thd->set_query_id;

  /* TODO: Think more about consequences of this step. */
  thd->set_query_id= 0;
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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),
                            0, 0, &field_idx);
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  thd->set_query_id= save_set_query_id;
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  triggers= table->triggers;
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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);
}


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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. :)
    FIXME may be we still should bother about permissions here.
  */
  DBUG_ASSERT(fixed == 0);
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  if (field_idx != (uint)-1)
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  {
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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;
    return 0;
  }

  my_error(ER_BAD_FIELD_ERROR, MYF(0), field_name,
           (row_version == NEW_ROW) ? "NEW" : "OLD");
  return 1;
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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()
{
  /*
    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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/*
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  If item is a const function, calculate it and return a const item
  The original item is freed if not returned
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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;
5066
  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;
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  return REAL_RESULT;
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}


5077
void resolve_const_item(THD *thd, Item **ref, Item *comp_item)
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{
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  Item *item= *ref;
  Item *new_item;
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  if (item->basic_const_item())
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    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

5087
  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;
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    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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  }
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  case REAL_RESULT:
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  {						// It must REAL_RESULT
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    double result= item->val_real();
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    uint length=item->max_length,decimals=item->decimals;
    bool null_value=item->null_value;
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    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;
  }
  case ROW_RESULT:
  default:
    DBUG_ASSERT(0);
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  }
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  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
5160
    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);
  }
5175
  double result= item->val_real();
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  if (item->null_value)
    return 1;
  return result == field->val_real();
}

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Item_cache* Item_cache::get_cache(Item_result type)
{
5183
  switch (type) {
5184 5185 5186 5187
  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)
{
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  str->append("<cache>(", 8);
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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);
  return (longlong) (value+(value > 0 ? 0.5 : -0.5));
}


String* Item_cache_real::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  str->set(value, decimals, default_charset());
  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);
5270
  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;
}


5306 5307
void Item_cache_str::store(Item *item)
{
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  value_buff.set(buffer, sizeof(buffer), item->collation.collation);
5309
  value= item->str_result(&value_buff);
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  if ((null_value= item->null_value))
    value= 0;
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  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;
    */
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    value_buff.copy(*value);
    value= &value_buff;
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  }
}
5326

5327
double Item_cache_str::val_real()
5328 5329
{
  DBUG_ASSERT(fixed == 1);
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  int err_not_used;
  char *end_not_used;
5332
  if (value)
5333
    return my_strntod(value->charset(), (char*) value->ptr(),
5334 5335
		      value->length(), &end_not_used, &err_not_used);
  return (double) 0;
5336
}
5337 5338


5339 5340
longlong Item_cache_str::val_int()
{
5341
  DBUG_ASSERT(fixed == 1);
5342
  int err;
5343 5344
  if (value)
    return my_strntoll(value->charset(), value->ptr(),
5345
		       value->length(), 10, (char**) 0, &err);
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  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;
}

5360

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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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}

5369

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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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  {
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    Item *el= item->el(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;
}

5386

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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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  {
    values[i]->store(item->el(i));
    null_value|= values[i]->null_value;
  }
}

5398

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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;
}

5408

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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;
}

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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
    {
      values[i]->val_int();
      if (values[i]->null_value)
	return 1;
    }
  }
  return 0;
}

5439

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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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5447

5448 5449
Item_type_holder::Item_type_holder(THD *thd, Item *item)
  :Item(thd, item), enum_set_typelib(0), fld_type(get_real_type(item))
5450 5451
{
  DBUG_ASSERT(item->fixed);
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5453
  max_length= display_length(item);
5454
  maybe_null= item->maybe_null;
5455
  collation.set(item->collation);
5456
  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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}


5464
/*
5465
  Return expression type of Item_type_holder
5466 5467

  SYNOPSIS
5468
    Item_type_holder::result_type()
5469 5470

  RETURN
5471
     Item_result (type of internal MySQL expression result)
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*/

5474
Item_result Item_type_holder::result_type() const
5475
{
5476
  return Field::result_merge_type(fld_type);
5477
}
5478

5479

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/*
5481
  Find real field type of item
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  SYNOPSIS
5484
    Item_type_holder::get_real_type()
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  RETURN
5487
    type of field which should be created to store item value
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*/

5490
enum_field_types Item_type_holder::get_real_type(Item *item)
5491
{
5492
  switch(item->type())
5493
  {
5494
  case FIELD_ITEM:
5495
  {
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    /*
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      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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    */
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    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;
5506
  }
5507
  case SUM_FUNC_ITEM:
5508
  {
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    /*
      Argument of aggregate function sometimes should be asked about field
      type
    */
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    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)
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    {
5521
      /*
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        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.
5526
      */
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      switch (item->result_type()) {
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      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;
      }
5541
    }
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    break;
  default:
    break;
5545
  }
5546
  return item->field_type();
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}

5549
/*
5550 5551
  Find field type which can carry current Item_type_holder type and
  type of given Item.
5552 5553

  SYNOPSIS
5554 5555 5556
    Item_type_holder::join_types()
    thd     thread handler
    item    given item to join its parameters with this item ones
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  RETURN
5559 5560
    TRUE   error - types are incompatible
    FALSE  OK
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*/

5563
bool Item_type_holder::join_types(THD *thd, Item *item)
5564
{
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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));
5572
  fld_type= Field::field_type_merge(fld_type, get_real_type(item));
5573
  {
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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);
5579
  }
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  if (Field::result_merge_type(fld_type) == DECIMAL_RESULT)
5581
  {
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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);
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  }
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  else
    max_length= max(max_length, display_length(item));
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  if (Field::result_merge_type(fld_type) == STRING_RESULT)
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  {
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    const char *old_cs, *old_derivation;
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    old_cs= collation.collation->name;
    old_derivation= collation.derivation_name();
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    if (collation.aggregate(item->collation))
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    {
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      my_error(ER_CANT_AGGREGATE_2COLLATIONS, MYF(0),
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	       old_cs, old_derivation,
	       item->collation.collation->name,
	       item->collation.derivation_name(),
	       "UNION");
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      DBUG_RETURN(TRUE);
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    }
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  }
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  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();
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  DBUG_PRINT("info", ("become type: %d  len: %u  dec: %u",
                      (int) fld_type, max_length, (uint) decimals));
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  DBUG_RETURN(FALSE);
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}

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/*
  Calculate lenth for merging result for given Item type
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  SYNOPSIS
    Item_type_holder::real_length()
    item  Item for lrngth detection
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  RETURN
    length
*/
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uint32 Item_type_holder::display_length(Item *item)
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{
  if (item->type() == Item::FIELD_ITEM)
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    return ((Item_field *)item)->max_disp_length();
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  switch (item->field_type())
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  {
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  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:
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    return item->max_length;
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  case MYSQL_TYPE_TINY:
    return 4;
  case MYSQL_TYPE_SHORT:
    return 6;
  case MYSQL_TYPE_LONG:
    return 11;
  case MYSQL_TYPE_FLOAT:
    return 25;
  case MYSQL_TYPE_DOUBLE:
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    return 53;
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  case MYSQL_TYPE_NULL:
    return 4;
  case MYSQL_TYPE_LONGLONG:
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    return 20;
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  case MYSQL_TYPE_INT24:
    return 8;
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  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;
  switch (fld_type)
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  {
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  case MYSQL_TYPE_ENUM:
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    DBUG_ASSERT(enum_set_typelib);
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    return new Field_enum((char *) 0, max_length, null_ptr, 0,
                          Field::NONE, name,
                          table, get_enum_pack_length(enum_set_typelib->count),
                          enum_set_typelib, collation.collation);
  case MYSQL_TYPE_SET:
    DBUG_ASSERT(enum_set_typelib);
    return new Field_set((char *) 0, max_length, null_ptr, 0,
                         Field::NONE, name,
                         table, get_set_pack_length(enum_set_typelib->count),
                         enum_set_typelib, collation.collation);
  default:
    break;
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  }
  return tmp_table_field_from_field_type(table);
}


/*
  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