support of subselect without FROM reducing (SCRUM)

fixed bug of calling setup_fields without correct lex->current_select pointer in mysql_derived
more correct creation of reference in Item_field::fix_field

mysql-test/r/subselect.result

 select (select 2);
 (select 2)
 2
+explain select (select 2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
 SELECT (SELECT 1) UNION SELECT (SELECT 2);
 (SELECT 1)
 1
 2
+explain SELECT (SELECT 1) UNION SELECT (SELECT 2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+3	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
+Note	1247	Select 4 was reduced during optimisation
 SELECT (SELECT (SELECT 0 UNION SELECT 0));
 (SELECT (SELECT 0 UNION SELECT 0))
 0
+explain SELECT (SELECT (SELECT 0 UNION SELECT 0));
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+3	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+4	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
 SELECT (SELECT 1 FROM (SELECT 1) as b HAVING a=1) as a;
 Reference 'a' not supported (forward reference in item list)
 SELECT (SELECT 1 FROM (SELECT 1) as b HAVING b=1) as a,(SELECT 1 FROM (SELECT 1) as c HAVING a=1) as b;
@@ -20,8 +39,9 @@ Reference 'a' not supported (forward reference in item list)
 EXPLAIN SELECT 1 FROM (SELECT 1 as a) as b  HAVING (SELECT a)=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
-3	DEPENDENT SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 3 was reduced during optimisation
 SELECT 1 FROM (SELECT 1 as a) as b HAVING (SELECT a)=1;
 1
 1
@@ -629,6 +649,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t	ref	id	id	5	const	1	Using where; Using index
 3	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 Warnings:
+Note	1247	Select 3 was reduced during optimisation
 Note	1247	Select 2 was reduced during optimisation
 EXPLAIN SELECT * FROM t WHERE id IN (SELECT 1 UNION SELECT 3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -752,6 +773,16 @@ NULL
 select 10.5 > ANY (SELECT * from t);
 10.5 > ANY (SELECT * from t)
 1
+explain select (select a+1) from t;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t	ALL	NULL	NULL	NULL	NULL	3	
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
+select (select a+1) from t;
+(select a+1)
+2.5
+NULL
+4.5
 drop table t;
 create table t (a float);
 select 10.5 IN (SELECT * from t LIMIT 1);

mysql-test/t/subselect.test

 select (select 2);
+explain select (select 2);
 SELECT (SELECT 1) UNION SELECT (SELECT 2);
+explain SELECT (SELECT 1) UNION SELECT (SELECT 2);
 SELECT (SELECT (SELECT 0 UNION SELECT 0));
+explain SELECT (SELECT (SELECT 0 UNION SELECT 0));
 -- error 1245
 SELECT (SELECT 1 FROM (SELECT 1) as b HAVING a=1) as a;
 -- error 1245
@@ -424,6 +427,8 @@ select 1.5 > ALL (SELECT * from t);
 select 10.5 > ALL (SELECT * from t);
 select 1.5 > ANY (SELECT * from t);
 select 10.5 > ANY (SELECT * from t);
+explain select (select a+1) from t;
+select (select a+1) from t;
 drop table t;
 
 #LIMIT is not supported now
@@ -433,6 +438,7 @@ select 10.5 IN (SELECT * from t LIMIT 1);
 -- error 1235
 select 10.5 IN (SELECT * from t LIMIT 1 UNION SELECT 1.5);
 drop table t;
+
 create table t1 (a int, b int, c varchar(10));
 create table t2 (a int);
 insert into t1 values (1,2,'a'),(2,3,'b'),(3,4,'c');

sql/item.cc

@@ -546,8 +546,11 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
   if (!field)					// If field is not checked
   {
-    Field *tmp;
-    if ((tmp= find_field_in_tables(thd, this, tables, 0)) == not_found_field)
+    TABLE_LIST *where= 0;
+    Field *tmp= (Field *)not_found_field;
+    if (outer_resolving || 
+	(tmp= find_field_in_tables(thd, this, tables, &where, 0)) ==
+	not_found_field)
     {
       /*
 	We can't find table field in table list of current select, 
@@ -565,12 +568,12 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
       SELECT_LEX *cursel=(SELECT_LEX *) thd->lex.current_select;
       if (cursel->master_unit()->first_select()->linkage !=
 	  DERIVED_TABLE_TYPE)
-	for (SELECT_LEX *sl=cursel->outer_select();
+	for (SELECT_LEX *sl=(outer_resolving?cursel:cursel->outer_select());
 	     sl;
 	     sl= sl->outer_select())
 	{
 	  if ((tmp= find_field_in_tables(thd, this,
-					 (last= sl)->get_table_list(),
+					 (last= sl)->get_table_list(), &where,
 					 0)) != not_found_field)
 	    break;
 	  if ((refer= find_item_in_list(this, sl->item_list,
@@ -588,7 +591,7 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
       else if (tmp == not_found_field && refer == (Item **)not_found_item)
       {
 	// call to return error code
-	find_field_in_tables(thd, this, tables, 1);
+	find_field_in_tables(thd, this, tables, &where, 1);
 	return -1;
       }
       else if (refer != (Item **)not_found_item)
@@ -614,6 +617,17 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 	  found table as depended (of select where was found table)
 	*/
 	thd->lex.current_select->mark_as_dependent(last);
+	if (depended_from->having_fix_field)
+	{
+	  Item_ref *rf;
+	  *ref= rf= new Item_ref((where->db[0]?where->db:0), 
+				 (char *)where->alias,
+				 (char *)field_name);
+	  if (!rf)
+	    return 1;
+	  (rf)->outer_resolving= outer_resolving;
+	  return rf->check_cols(1) || rf->fix_fields(thd, tables, ref);
+	}
       }
     } 
     else if (!tmp)
@@ -629,14 +643,6 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     table->used_fields++;
     table->used_keys&=field->part_of_key;
   }
-  if (depended_from != 0 && depended_from->having_fix_field)
-  {
-    *ref= new Item_ref((char *)db_name, (char *)table_name,
-		       (char *)field_name);
-    if (!*ref)
-      return 1;
-    return (*ref)->check_cols(1) || (*ref)->fix_fields(thd, tables, ref);
-  }
   fixed= 1;
   return 0;
 }
@@ -1007,13 +1013,17 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 {
   if (!ref)
   {
-    SELECT_LEX *sl= thd->lex.current_select->outer_select();
+    TABLE_LIST *where= 0;
+    SELECT_LEX *sl= (outer_resolving?
+		     thd->lex.current_select->select_lex():
+		     thd->lex.current_select->outer_select());
     /*
       Finding only in current select will be performed for selects that have 
       not outer one and for derived tables (which not support using outer 
       fields for now)
     */
-    if ((ref= find_item_in_list(this, 
+    if (outer_resolving ||
+	(ref= find_item_in_list(this, 
 				*(thd->lex.current_select->get_item_list()),
 				((sl && 
 				  thd->lex.current_select->master_unit()->
@@ -1041,7 +1051,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	   (Item **)not_found_item)
 	  break;
 	if ((tmp= find_field_in_tables(thd, this,
-				       sl->get_table_list(),
+				       sl->get_table_list(), &where,
 				       0)) != not_found_field);
 	if (sl->master_unit()->first_select()->linkage ==
 	    DERIVED_TABLE_TYPE)

sql/item.h

@@ -96,6 +96,7 @@ class Item {
   CHARSET_INFO *thd_charset() const;
   CHARSET_INFO *charset() const { return str_value.charset(); };
   void set_charset(CHARSET_INFO *cs) { str_value.set_charset(cs); }
+  virtual void set_outer_resolving() {}
 
   // Row emulation
   virtual uint cols() { return 1; }
@@ -117,12 +118,14 @@ class Item_ident :public Item
   const char *table_name;
   const char *field_name;
   st_select_lex *depended_from;
+  bool outer_resolving; /* used for items from reduced subselect */
   Item_ident(const char *db_name_par,const char *table_name_par,
 	     const char *field_name_par)
-    :db_name(db_name_par),table_name(table_name_par),
-    field_name(field_name_par), depended_from(0)
+    :db_name(db_name_par), table_name(table_name_par),
+     field_name(field_name_par), depended_from(0), outer_resolving(0)
     { name = (char*) field_name_par; }
   const char *full_name() const;
+  void set_outer_resolving() { outer_resolving= 1; }
 };
 
 

sql/item_cmpfunc.cc

@@ -946,6 +946,13 @@ Item_func_case::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
   return 0;
 }
 
+void Item_func_case::set_outer_resolving()
+{
+  first_expr->set_outer_resolving();
+  else_expr->set_outer_resolving();
+  Item_func::set_outer_resolving();
+}
+
 bool Item_func_case::check_loop(uint id)
 {
   DBUG_ENTER("Item_func_case::check_loop");
@@ -1523,6 +1530,15 @@ bool Item_cond::check_loop(uint id)
   DBUG_RETURN(0);
 }
 
+void Item_cond::set_outer_resolving()
+{
+  Item_func::set_outer_resolving();
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item= li++))
+    item->set_outer_resolving();
+}
+
 void Item_cond::split_sum_func(List<Item> &fields)
 {
   List_iterator<Item> li(list);

sql/item_cmpfunc.h

@@ -277,6 +277,11 @@ class Item_func_interval :public Item_int_func
   const char *func_name() const { return "interval"; }
   void update_used_tables();
   bool check_loop(uint id);
+  void set_outer_resolving()
+  {
+    item->set_outer_resolving();
+    Item_func::set_outer_resolving();
+  }
 };
 
 
@@ -359,6 +364,7 @@ class Item_func_case :public Item_func
   bool fix_fields(THD *thd, struct st_table_list *tlist, Item **ref);
   Item *find_item(String *str);
   bool check_loop(uint id);
+  void set_outer_resolving();
 };
 
 
@@ -643,6 +649,11 @@ class Item_func_in :public Item_int_func
     DBUG_RETURN(item->check_loop(id));
   }
   bool nulls_in_row();
+  void set_outer_resolving()
+  {
+    item->set_outer_resolving();
+    Item_int_func::set_outer_resolving();
+  }
 };
 
 /* Functions used by where clause */
@@ -784,6 +795,7 @@ class Item_cond :public Item_bool_func
   friend int setup_conds(THD *thd,TABLE_LIST *tables,COND **conds);
   bool check_loop(uint id);
   void top_level_item() { abort_on_null=1; }
+  void set_outer_resolving();
 };
 
 

sql/item_func.cc

@@ -146,6 +146,16 @@ bool Item_func::check_loop(uint id)
   DBUG_RETURN(0);
 }
 
+void Item_func::set_outer_resolving()
+{
+  if (arg_count)
+  {
+    Item **arg,**arg_end;
+    for (arg= args, arg_end= args+arg_count; arg != arg_end; arg++)
+      (*arg)->set_outer_resolving();
+  }
+}
+
 void Item_func::split_sum_func(List<Item> &fields)
 {
   Item **arg,**arg_end;
@@ -2356,6 +2366,15 @@ bool Item_func_match::check_loop(uint id)
   DBUG_RETURN(0);
 }
 
+void Item_func_match::set_outer_resolving()
+{
+  Item_real_func::set_outer_resolving();
+  List_iterator<Item> li(fields);
+  Item *item;
+  while ((item= li++))
+    item->set_outer_resolving();
+}
+
 bool Item_func_match::fix_index()
 {
   List_iterator_fast<Item> li(fields);

sql/item_func.h

@@ -133,6 +133,7 @@ class Item_func :public Item_result_field
   friend class udf_handler;
   Field *tmp_table_field(TABLE *t_arg);
   bool check_loop(uint id);
+  void set_outer_resolving();
 };
 
 
@@ -632,6 +633,11 @@ class Item_func_field :public Item_int_func
       DBUG_RETURN(1);
     DBUG_RETURN(item->check_loop(id));
   }
+  void set_outer_resolving()
+  {
+    item->set_outer_resolving();
+    Item_int_func::set_outer_resolving();
+  }
 };
 
 
@@ -1006,6 +1012,7 @@ class Item_func_match :public Item_real_func
   bool fix_index();
   void init_search(bool no_order);
   bool check_loop(uint id);
+  void set_outer_resolving();
 };
 
 

sql/item_row.cc

@@ -105,5 +105,20 @@ void Item_row::bring_value()
 {
   for (uint i= 0; i < arg_count; i++)
     items[i]->bring_value();
-  return;
+}
+
+void Item_row::set_outer_resolving()
+{
+  for (uint i= 0; i < arg_count; i++)
+    items[i]->set_outer_resolving();
+}
+
+bool Item_row::check_loop(uint id)
+{
+  if (Item::check_loop(id))
+    return 1;
+  for (uint i= 0; i < arg_count; i++)
+    if (items[i]->check_loop(id))
+      return 1;
+  return 0;
 }

sql/item_row.h

@@ -64,6 +64,8 @@ class Item_row: public Item
   bool const_item() const { return const_item_cache; };
   enum Item_result result_type() const { return ROW_RESULT; }
   void update_used_tables();
+  bool check_loop(uint id);
+  void set_outer_resolving();
 
   uint cols() { return arg_count; }
   Item* el(uint i) { return items[i]; }

sql/item_strfunc.h

@@ -116,6 +116,11 @@ class Item_func_concat_ws :public Item_str_func
       DBUG_RETURN(1);
     DBUG_RETURN(separator->check_loop(id));
   }
+  void set_outer_resolving()
+  {
+    separator->set_outer_resolving();
+    Item_func::set_outer_resolving();
+  }
 };
 
 class Item_func_reverse :public Item_str_func
@@ -393,6 +398,11 @@ class Item_func_elt :public Item_str_func
       DBUG_RETURN(1);
     DBUG_RETURN(item->check_loop(id));
   }
+  void set_outer_resolving()
+  {
+    item->set_outer_resolving();
+    Item_str_func::set_outer_resolving();
+  }
 };
 
 
@@ -421,6 +431,11 @@ class Item_func_make_set :public Item_str_func
       DBUG_RETURN(1);
     DBUG_RETURN(item->check_loop(id));
   }
+  void set_outer_resolving()
+  {
+    item->set_outer_resolving();
+    Item_str_func::set_outer_resolving();
+  }
 };
 
 

sql/item_subselect.cc

@@ -146,6 +146,54 @@ void Item_singlerow_subselect::reset()
     value->null_value= 1;
 }
 
+void Item_singlerow_subselect::select_transformer(st_select_lex_unit *unit)
+{
+  SELECT_LEX *select_lex= unit->first_select();
+  
+  if (!select_lex->next_select() && !select_lex->table_list.elements &&
+      select_lex->item_list.elements == 1)
+  {
+    
+    have_to_be_excluded= 1;
+    THD *thd= current_thd;
+    if (thd->lex.describe)
+    {
+      char warn_buff[MYSQL_ERRMSG_SIZE];
+      sprintf(warn_buff, ER(ER_SELECT_REDUCED), select_lex->select_number);
+      push_warning(thd, MYSQL_ERROR::WARN_LEVEL_NOTE,
+		   ER_SELECT_REDUCED, warn_buff);
+    }
+    substitution= select_lex->item_list.head();
+    substitution->set_outer_resolving();
+    if (substitution->type() == FIELD_ITEM ||
+	substitution->type() == REF_ITEM)
+      name= substitution->name; // Save name for correct resolving
+     
+    if (select_lex->where || select_lex->having)
+    {
+      Item *cond;
+      if (!select_lex->having)
+	cond= select_lex->where;
+      else if (!select_lex->where)
+	cond= select_lex->having;
+      else
+	if (!(cond= new Item_cond_and(select_lex->having, select_lex->where)))
+	{
+	  my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
+	  thd->fatal_error= 1;
+	  return;
+	}
+      if (!(substitution= new Item_func_if(cond, substitution,
+					   new Item_null())))
+      {
+	my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
+	thd->fatal_error= 1;
+	return;
+      }
+    }
+  }
+}
+
 void Item_singlerow_subselect::store(uint i, Item *item)
 {
   row[i]->store(item);

sql/item_subselect.h

@@ -106,6 +106,7 @@ class Item_singlerow_subselect :public Item_subselect
     decimals= item->decimals;
   }
   void reset();
+  void select_transformer(st_select_lex_unit *unit);
   void store(uint i, Item* item);
   double val();
   longlong val_int ();

sql/mysql_priv.h

@@ -463,7 +463,7 @@ bool drop_locked_tables(THD *thd,const char *db, const char *table_name);
 void abort_locked_tables(THD *thd,const char *db, const char *table_name);
 extern const Field *not_found_field;
 Field *find_field_in_tables(THD *thd, Item_ident *item, TABLE_LIST *tables,
-			    bool report_error);
+			    TABLE_LIST **where, bool report_error);
 Field *find_field_in_table(THD *thd,TABLE *table,const char *name,uint length,
 			   bool check_grant,bool allow_rowid);
 #ifdef HAVE_OPENSSL

sql/sql_base.cc

@@ -1654,6 +1654,7 @@ const Field *not_found_field= (Field*) 0x1;
     thd - pointer to current thread structure
     item - field item that should be found
     tables - tables for scaning
+    where - table where field found will be returned via this parameter
     report_error - if FALSE then do not report error if item not found and 
       return not_found_field;
 
@@ -1667,7 +1668,7 @@ const Field *not_found_field= (Field*) 0x1;
 
 Field *
 find_field_in_tables(THD *thd, Item_ident *item, TABLE_LIST *tables,
-		     bool report_error)
+		     TABLE_LIST **where, bool report_error)
 {
   Field *found=0;
   const char *db=item->db_name;
@@ -1688,6 +1689,7 @@ find_field_in_tables(THD *thd, Item_ident *item, TABLE_LIST *tables,
 					grant_option && !thd->master_access,1);
 	if (find)
 	{
+	  (*where)= tables;
 	  if (find == WRONG_GRANT)
 	    return (Field*) 0;
 	  if (db || !thd->where)
@@ -1742,6 +1744,7 @@ find_field_in_tables(THD *thd, Item_ident *item, TABLE_LIST *tables,
     {
       if (field == WRONG_GRANT)
 	return (Field*) 0;
+      (*where)= tables;
       if (found)
       {
 	if (!thd->where)			// Returns first found

sql/sql_derived.cc

@@ -63,6 +63,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
   TMP_TABLE_PARAM tmp_table_param;
   bool is_union=sl->next_select() && sl->next_select()->linkage == UNION_TYPE;
   DBUG_ENTER("mysql_derived");
+  SELECT_LEX_NODE *save_current_select= lex->current_select;
   
 
 /*
@@ -111,6 +112,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
       }
     }
 
+    lex->current_select= sl;
     if (setup_fields(thd,tables,item_list,0,0,1))
     {
       res=-1;
@@ -119,7 +121,8 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
     bzero((char*) &tmp_table_param,sizeof(tmp_table_param));
     tmp_table_param.field_count=item_list.elements;
     if (!(table=create_tmp_table(thd, &tmp_table_param, item_list,
-			         (ORDER*) 0, is_union && !unit->union_option, 1,
+			         (ORDER*) 0, 
+				 is_union && !unit->union_option, 1,
 			         (sl->options | thd->options |
 				  TMP_TABLE_ALL_COLUMNS),
                                  HA_POS_ERROR)))
@@ -138,8 +141,6 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
       if (unit->select_limit_cnt == HA_POS_ERROR)
 	sl->options&= ~OPTION_FOUND_ROWS;
 
-      SELECT_LEX_NODE *save_current_select= lex->current_select;
-      lex->current_select= sl;
       if (is_union)
 	res=mysql_union(thd,lex,derived_result,unit);
       else
@@ -149,7 +150,6 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
 			sl->having, (ORDER*) NULL,
 			sl->options | thd->options  | SELECT_NO_UNLOCK,
 			derived_result, unit, sl, 0);
-      lex->current_select= save_current_select;
 
       if (!res)
       {
@@ -184,6 +184,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
     if (res)
       free_tmp_table(thd,table);
 exit:
+    lex->current_select= save_current_select;
     close_thread_tables(thd);
   }
   DBUG_RETURN(res);