simple subselects ported to new select_lex structures

include/mysqld_error.h:
  simple subselects
libmysqld/Makefile.am:
  simple subselects
sql/Makefile.am:
  simple subselects
sql/item.h:
  simple subselects
sql/item_strfunc.h:
  simple subselects
sql/share/czech/errmsg.txt:
  simple subselects
sql/share/danish/errmsg.txt:
  simple subselects
sql/share/dutch/errmsg.txt:
  simple subselects
sql/share/english/errmsg.txt:
  simple subselects
sql/share/estonian/errmsg.txt:
  simple subselects
sql/share/french/errmsg.txt:
  simple subselects
sql/share/german/errmsg.txt:
  simple subselects
sql/share/greek/errmsg.txt:
  simple subselects
sql/share/hungarian/errmsg.txt:
  simple subselects
sql/share/italian/errmsg.txt:
  simple subselects
sql/share/japanese/errmsg.txt:
  simple subselects
sql/share/korean/errmsg.txt:
  simple subselects
sql/share/norwegian-ny/errmsg.txt:
  simple subselects
sql/share/norwegian/errmsg.txt:
  simple subselects
sql/share/polish/errmsg.txt:
  simple subselects
sql/share/portuguese/errmsg.txt:
  simple subselects
sql/share/romanian/errmsg.txt:
  simple subselects
sql/share/russian/errmsg.txt:
  simple subselects
sql/share/slovak/errmsg.txt:
  simple subselects
sql/share/spanish/errmsg.txt:
  simple subselects
sql/share/swedish/errmsg.txt:
  simple subselects
sql/share/ukrainian/errmsg.txt:
  simple subselects
sql/sql_class.cc:
  simple subselects
sql/sql_class.h:
  simple subselects
sql/sql_lex.cc:
  simple subselects
sql/sql_select.cc:
  simple subselects
sql/sql_select.h:
  simple subselects
sql/sql_union.cc:
  simple subselects
sql/sql_yacc.yy:
  simple subselects

include/mysqld_error.h

@@ -243,4 +243,6 @@
 #define ER_MIXING_NOT_ALLOWED 1224
 #define ER_DUP_ARGUMENT 1225
 #define ER_USER_LIMIT_REACHED 1226
-#define ER_ERROR_MESSAGES 227
+#define ER_SUBSELECT_NO_1_COL 1227
+#define ER_SUBSELECT_NO_1_ROW 1228
+#define ER_ERROR_MESSAGES 229

libmysqld/Makefile.am

@@ -43,7 +43,8 @@ sqlsources = convert.cc derror.cc field.cc field_conv.cc filesort.cc \
 	hostname.cc init.cc \
 	item.cc item_buff.cc item_cmpfunc.cc item_create.cc \
 	item_func.cc item_strfunc.cc item_sum.cc item_timefunc.cc \
-	item_uniq.cc key.cc lock.cc log.cc log_event.cc mf_iocache.cc\
+	item_uniq.cc item_subselect.cc \
+	key.cc lock.cc log.cc log_event.cc mf_iocache.cc\
 	mini_client.cc net_pkg.cc net_serv.cc opt_ft.cc opt_range.cc \
 	opt_sum.cc procedure.cc records.cc sql_acl.cc \
 	repl_failsafe.cc slave.cc \

mysql-test/r/subselect.result

+drop table if exists t1,t2,t3,t4;
+create table t1 (a int);
+create table t2 (a int, b int);
+create table t3 (a int);
+create table t4 (a int, b int);
+insert into t1 values (2);
+insert into t2 values (1,7),(2,7);
+insert into t4 values (4,8),(3,8),(5,9);
+select (select a from t1), a from t2;
+(select a from t1)	a
+2	1
+2	2
+select (select a from t3), a from t2;
+(select a from t3)	a
+NULL	1
+NULL	2
+select * from t2 where t2.a=(select a from t1);
+a	b
+2	7
+insert into t3 values (6),(7),(3);
+select * from t2 where t2.b=(select a from t3 order by 1 limit 1);
+a	b
+1	7
+2	7
+select * from t2 where t2.b=(select a from t3 order by 1 limit 1) 
+union (select * from t4 order by a limit 2) limit 3;
+a	b
+1	7
+2	7
+3	8
+drop table t1,t2,t3,t4;

mysql-test/t/subselect.test

+
+#select (select 2);
+drop table if exists t1,t2,t3,t4;
+create table t1 (a int);
+create table t2 (a int, b int);
+create table t3 (a int);
+create table t4 (a int, b int);
+insert into t1 values (2);
+insert into t2 values (1,7),(2,7);
+insert into t4 values (4,8),(3,8),(5,9);
+select (select a from t1), a from t2;
+select (select a from t3), a from t2;
+select * from t2 where t2.a=(select a from t1);
+insert into t3 values (6),(7),(3);
+select * from t2 where t2.b=(select a from t3 order by 1 limit 1);
+select * from t2 where t2.b=(select a from t3 order by 1 limit 1) 
+union (select * from t4 order by a limit 2) limit 3;
+drop table t1,t2,t3,t4;

sql/Makefile.am

@@ -46,7 +46,7 @@ mysqld_LDADD =		@MYSQLD_EXTRA_LDFLAGS@ \
 			$(LDADD)  $(CXXLDFLAGS) $(WRAPLIBS) @LIBDL@ @openssl_libs@
 noinst_HEADERS =	item.h item_func.h item_sum.h item_cmpfunc.h \
 			item_strfunc.h item_timefunc.h item_uniq.h \
-			item_create.h mysql_priv.h \
+			item_create.h item_subselect.h mysql_priv.h \
 			procedure.h sql_class.h sql_lex.h sql_list.h \
 			sql_manager.h sql_map.h sql_string.h unireg.h \
 			field.h handler.h \
@@ -60,7 +60,7 @@ noinst_HEADERS =	item.h item_func.h item_sum.h item_cmpfunc.h \
 mysqld_SOURCES =	sql_lex.cc sql_handler.cc \
 			item.cc item_sum.cc item_buff.cc item_func.cc \
 			item_cmpfunc.cc item_strfunc.cc item_timefunc.cc \
-			thr_malloc.cc item_create.cc \
+			thr_malloc.cc item_create.cc item_subselect.cc\
 			field.cc key.cc sql_class.cc sql_list.cc \
 			net_serv.cc net_pkg.cc lock.cc my_lock.c \
 			sql_string.cc sql_manager.cc sql_map.cc \

sql/item.h

@@ -32,7 +32,8 @@ class Item {
   enum Type {FIELD_ITEM,FUNC_ITEM,SUM_FUNC_ITEM,STRING_ITEM,
 	     INT_ITEM,REAL_ITEM,NULL_ITEM,VARBIN_ITEM,
 	     COPY_STR_ITEM,FIELD_AVG_ITEM,
-	     PROC_ITEM,COND_ITEM,REF_ITEM,FIELD_STD_ITEM, CONST_ITEM};
+	     PROC_ITEM,COND_ITEM,REF_ITEM,FIELD_STD_ITEM, CONST_ITEM,
+             SUBSELECT_ITEM};
   enum cond_result { COND_UNDEF,COND_OK,COND_TRUE,COND_FALSE };
 
   String str_value;			/* used to store value */
@@ -46,7 +47,6 @@ class Item {
   my_bool unsigned_flag;
   my_bool with_sum_func;
 
-
   // alloc & destruct is done as start of select using sql_alloc
   Item();
   virtual ~Item() { name=0; }		/*lint -e1509 */
@@ -371,6 +371,7 @@ class Item_ref :public Item_ident
 #include "item_strfunc.h"
 #include "item_timefunc.h"
 #include "item_uniq.h"
+#include "item_subselect.h"
 
 class Item_copy_string :public Item
 {
@@ -458,3 +459,4 @@ extern Item_result item_cmp_type(Item_result a,Item_result b);
 extern Item *resolve_const_item(Item *item,Item *cmp_item);
 extern bool field_is_equal_to_item(Field *field,Item *item);
 Item *get_system_var(LEX_STRING name);
+

sql/item_strfunc.h

@@ -38,7 +38,9 @@ class Item_str_func :public Item_func
   Field *tmp_table_field(TABLE *t_arg)
   {
     if (!t_arg) return result_field;
-    return (max_length > 255) ? (Field *)new Field_blob(max_length,maybe_null, name,t_arg, binary) : (Field *) new Field_string(max_length,maybe_null, name,t_arg, binary);
+    return (max_length > 255) ? 
+      (Field *) new Field_blob(max_length,maybe_null, name,t_arg, binary) : 
+      (Field *) new Field_string(max_length,maybe_null, name,t_arg, binary);
   }  
 };
 

sql/item_subselect.cc

+/* Copyright (C) 2000 MySQL AB
+
+   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.
+
+   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.
+
+   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 */
+
+/* 
+   subselect Item
+
+SUBSELECT TODO:
+   - add function from mysql_select that use JOIN* as parameter to JOIN methods
+     (sql_select.h/sql_select.cc)
+   - remove double 'having' & 'having_list' from JOIN
+     (sql_select.h/sql_select.cc)
+
+   - add subselect union select (sql_union.cc)
+   - depended from outer select subselects
+   
+*/
+
+#ifdef __GNUC__
+#pragma implementation				// gcc: Class implementation
+#endif
+
+#include "mysql_priv.h"
+#include "sql_select.h"
+
+Item_subselect::Item_subselect(THD *thd, st_select_lex *select_lex):
+  executed(0)
+{
+  DBUG_ENTER("Item_subselect::Item_subselect");
+  DBUG_PRINT("subs", ("select_lex 0x%xl", (long) select_lex));
+  result= new select_subselect(this);
+  join= new JOIN(thd, select_lex->item_list, select_lex->options, result);
+  this->select_lex= select_lex;
+  maybe_null= 1;
+  /*
+    item value is NULL if select_subselect not changed this value 
+    (i.e. some rows will be found returned)
+  */
+  assign_null(); 
+  DBUG_VOID_RETURN;
+}
+
+Item::Type Item_subselect::type() const 
+{
+  return SUBSELECT_ITEM;
+}
+
+double Item_subselect::val () 
+{
+  if (exec())
+    return 0;
+  return real_value;
+}
+
+longlong Item_subselect::val_int () 
+{
+  if (exec())
+    return 0;
+  return int_value;
+}
+
+String *Item_subselect::val_str (String *str) 
+{
+  if (exec() || null_value)
+    return 0;
+  return &str_value;
+}
+
+void Item_subselect::make_field (Send_field *tmp_field)
+{
+  if (null_value)
+  {
+    init_make_field(tmp_field,FIELD_TYPE_NULL);
+    tmp_field->length=4;
+  } else {
+    init_make_field(tmp_field, ((result_type() == STRING_RESULT) ?
+				FIELD_TYPE_VAR_STRING :
+				(result_type() == INT_RESULT) ?
+				FIELD_TYPE_LONGLONG : FIELD_TYPE_DOUBLE));
+  }
+}
+
+bool Item_subselect::fix_fields(THD *thd,TABLE_LIST *tables)
+{
+  // Is it one field subselect?
+  if (select_lex->item_list.elements != 1)
+  {  
+    my_printf_error(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL), MYF(0));
+    return 1;
+  }
+  SELECT_LEX *save_select= thd->lex.select;
+  thd->lex.select= select_lex;
+  if(join->prepare((TABLE_LIST*) select_lex->table_list.first,
+		   select_lex->where,
+		   (ORDER*) select_lex->order_list.first,
+		   (ORDER*) select_lex->group_list.first,
+		   select_lex->having,
+		   (ORDER*) 0, select_lex, 
+		   (SELECT_LEX_UNIT*) select_lex->master))
+    return 1;
+  if (join->optimize())
+  {
+    executed= 1;
+    return 1;
+  }
+  thd->lex.select= save_select;
+  return 0;
+}
+
+int Item_subselect::exec()
+{
+  if (!executed)
+  {
+    SELECT_LEX *save_select= join->thd->lex.select;
+    join->thd->lex.select= select_lex;
+    join->exec();
+    join->thd->lex.select= save_select;
+    if (!executed)
+      //No rows returned => value is null (returned as inited)
+      executed= 1;
+    return join->error;
+  }
+  return 0;
+}

sql/item_subselect.h

+/* Copyright (C) 2000 MySQL AB
+
+   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.
+
+   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.
+
+   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 */
+
+/* subselect Item */
+
+#ifdef __GNUC__
+#pragma interface			/* gcc class implementation */
+#endif
+
+struct st_select_lex;
+class JOIN;
+class select_subselect;
+
+/* simple (not depended of covered select ) subselect */
+
+class Item_subselect :public Item
+{
+protected:
+  my_bool executed; /* simple subselect is executed */
+  longlong int_value;
+  double real_value;
+  enum Item_result res_type;
+
+  int exec();
+  void assign_null() 
+  {
+    null_value= 1;
+    int_value= 0;
+    real_value= 0;
+    max_length= 4;
+    res_type= STRING_RESULT;
+  }
+public:
+  st_select_lex *select_lex;
+  JOIN *join;
+  select_subselect *result;
+
+  Item_subselect(THD *thd, st_select_lex *select_lex);
+  Item_subselect(Item_subselect *item)
+  {
+    null_value= item->null_value;
+    int_value= item->int_value;
+    real_value= item->real_value;
+    max_length= item->max_length;
+    decimals= item->decimals;
+    res_type= item->res_type;
+    executed= item->executed;
+    select_lex= item->select_lex;
+    join= item->join;
+    result= item->result;
+    name= item->name;
+  }
+  enum Type type() const;
+  double val ();
+  longlong val_int ();
+  String *val_str (String *);
+  bool is_null() { return null_value; }
+  void make_field (Send_field *);
+  bool fix_fields(THD *thd, TABLE_LIST *tables);
+  Item *new_item() { return new Item_subselect(this); }
+  enum Item_result result_type() const { return res_type; }
+
+  friend class select_subselect;
+};
+
+

sql/share/czech/errmsg.txt

@@ -237,3 +237,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/danish/errmsg.txt

@@ -231,3 +231,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/dutch/errmsg.txt

@@ -236,3 +236,5 @@
 "Het combineren van transactionele en niet-transactionele tabellen is uitgeschakeld.",
 "Optie '%s' tweemaal gebruikt in opdracht",
 "Gebruiker '%-64s' heeft het maximale gebruik van de '%s' faciliteit overschreden (huidige waarde: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/english/errmsg.txt

@@ -228,3 +228,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/estonian/errmsg.txt

@@ -233,3 +233,5 @@
 "Transaktsioone toetavate ning mittetoetavate tabelite kooskasutamine ei ole lubatud",
 "Mrangut '%s' on lauses kasutatud topelt",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/french/errmsg.txt

@@ -228,3 +228,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/german/errmsg.txt

@@ -231,3 +231,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/greek/errmsg.txt

@@ -228,3 +228,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/hungarian/errmsg.txt

@@ -230,3 +230,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/italian/errmsg.txt

@@ -228,3 +228,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/japanese/errmsg.txt

@@ -230,3 +230,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/korean/errmsg.txt

@@ -228,3 +228,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/norwegian-ny/errmsg.txt

@@ -230,3 +230,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/norwegian/errmsg.txt

@@ -230,3 +230,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/polish/errmsg.txt

@@ -232,3 +232,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/portuguese/errmsg.txt

@@ -228,3 +228,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/romanian/errmsg.txt

@@ -232,3 +232,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/russian/errmsg.txt

@@ -231,3 +231,5 @@
 "  transactional  non-transactional  ",
 " '%s'  ",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"    ",
+"    ",

sql/share/slovak/errmsg.txt

@@ -236,3 +236,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/spanish/errmsg.txt

@@ -229,3 +229,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/swedish/errmsg.txt

@@ -228,3 +228,5 @@
 "Blandning av transaktionella och icke-transaktionella tabeller är inaktiverat",
 "Option '%s' användes två gånger",
 "Användare '%-64s' har överskridit '%s' (nuvarande värde: %ld)",
+"Subselect return more than 1 field",
+"Subselect return more than 1 record",

sql/share/ukrainian/errmsg.txt

@@ -233,3 +233,5 @@
 "Mixing of transactional and non-transactional tables is disabled",
 "Option '%s' used twice in statement",
 "User '%-64s' has exceeded the '%s' resource (current value: %ld)",
+"i  i i 1 ",
+"i  i i 1 ",

sql/sql_class.cc

@@ -774,3 +774,30 @@ bool select_dump::send_eof()
   file= -1;
   return error;
 }
+
+select_subselect::select_subselect(Item_subselect *item)
+{
+  this->item=item;
+}
+
+bool select_subselect::send_data(List<Item> &items)
+{
+  if (item->executed){
+    my_printf_error(ER_SUBSELECT_NO_1_ROW, ER(ER_SUBSELECT_NO_1_ROW), MYF(0));
+    return 1;
+  }
+  Item *val_item= (Item *)item->select_lex->item_list.head();
+  if ((item->null_value= val_item->is_null()))
+  {
+    item->assign_null();
+  } else {
+    item->max_length= val_item->max_length;
+    item->decimals= val_item->decimals;
+    item->binary= val_item->binary;
+    val_item->val_str(&item->str_value);
+    item->int_value= val_item->val_int();
+    item->real_value= val_item->val();
+    item->res_type= val_item->result_type();
+  }
+  return 0;
+}

sql/sql_class.h

@@ -685,6 +685,19 @@ class select_union :public select_result {
   bool flush();
 };
 
+/* Single value subselect interface class */
+class select_subselect :public select_result
+{
+  Item_subselect *item;
+public:
+  select_subselect(Item_subselect *item);
+  bool send_fields(List<Item> &list, uint flag) { return 0; };
+  bool send_data(List<Item> &items);
+  bool send_eof() { return 0; };
+  
+  friend class Ttem_subselect;
+};
+
 /* Structs used when sorting */
 
 typedef struct st_sort_field {

sql/sql_lex.cc

@@ -901,6 +901,7 @@ void st_select_lex_node::init_select()
 
 void st_select_lex_unit::init_query()
 {
+  linkage= GLOBAL_OPTIONS_TYPE;
   st_select_lex_node::init_query();
   global_parameters= this;
   select_limit_cnt= HA_POS_ERROR;

sql/sql_select.h

@@ -149,8 +149,7 @@ class TMP_TABLE_PARAM {
   }
 };
 
-
-class JOIN {
+class JOIN :public Sql_alloc{
  public:
   JOIN_TAB *join_tab,**best_ref,**map2table;
   TABLE    **table,**all_tables,*sort_by_table;
@@ -175,6 +174,70 @@ class JOIN {
   MYSQL_LOCK *lock;
   // unit structure (with global parameters) for this select
   SELECT_LEX_UNIT *unit;
+  // select that processed
+  SELECT_LEX *select_lex;
+
+  bool select_distinct, //Is select distinct?
+    no_order, simple_order, simple_group,
+    skip_sort_order, need_tmp,
+    hidden_group_fields,
+    buffer_result;
+  DYNAMIC_ARRAY keyuse;
+  Item::cond_result cond_value;
+  List<Item> all_fields;
+  List<Item> & fields_list; // hold field list passed to mysql_select
+  int error;
+
+  ORDER *order, *group_list, *proc_param; //hold parameters of mysql_select
+  COND *conds;                            // ---"---
+  TABLE_LIST *tables_list;           //hold 'tables' parameter of mysql_selec
+  SQL_SELECT *select;                //created in optimisation phase
+  TABLE      *exec_tmp_table;        //used in 'exec' to hold temporary
+
+  my_bool test_function_query; // need to return select items 1 row
+  const char *zero_result_cause; // not 0 if exec must return zero result
+
+  JOIN(THD *thd, List<Item> &fields,
+       ulong select_options, select_result *result):
+    join_tab(0),
+    table(0),
+    tables(0), const_tables(0),
+    sort_and_group(0), first_record(0),
+    do_send_rows(1),
+    send_records(0), found_records(0), examined_rows(0),
+    thd(thd),
+    sum_funcs(0),
+    having(0),
+    select_options(select_options),
+    result(result),
+    lock(thd->lock),
+    select_lex(0), //for safety
+    select_distinct(test(select_options & SELECT_DISTINCT)),
+    no_order(0), simple_order(0), simple_group(0), skip_sort_order(0),
+    need_tmp(0),
+    hidden_group_fields (0), /*safety*/
+    buffer_result(test(select_options & OPTION_BUFFER_RESULT) &&
+		  !test(select_options & OPTION_FOUND_ROWS)),
+    all_fields(fields),
+    fields_list(fields),
+    select(0),
+    exec_tmp_table(0),
+    test_function_query(0),
+    zero_result_cause(0)
+  {
+    fields_list = fields;
+    bzero((char*) &keyuse,sizeof(keyuse));
+    tmp_table_param.copy_field=0;
+    tmp_table_param.end_write_records= HA_POS_ERROR;
+  }
+  
+  int prepare(TABLE_LIST *tables,
+	      COND *conds, ORDER *order, ORDER *group, Item *having,
+	      ORDER *proc_param, SELECT_LEX *select, SELECT_LEX_UNIT *unit);
+  int optimize();
+  int global_optimize();
+  void exec();
+  int cleanup(THD *thd);  
 };
 
 

sql/sql_select.h.rej

+***************
+*** 173,178 ****
+    select_result *result;
+    TMP_TABLE_PARAM tmp_table_param;
+    MYSQL_LOCK *lock;
+  };
+  
+  
+--- 172,240 ----
+    select_result *result;
+    TMP_TABLE_PARAM tmp_table_param;
+    MYSQL_LOCK *lock;
++ 
++   bool select_distinct, //Is select distinct?
++     no_order, simple_order, simple_group,
++     skip_sort_order, need_tmp,
++     hidden_group_fields,
++     buffer_result;
++   DYNAMIC_ARRAY keyuse;
++   Item::cond_result cond_value;
++   List<Item> all_fields;
++   List<Item> & fields_list; // hold field list passed to mysql_select
++   int error;
++     
++   ORDER *order, *group_list, *proc_param; //hold parameters of mysql_select
++   COND *conds;                            // ---"---
++   TABLE_LIST *tables_list;           //hold 'tables' parameter of mysql_select
++   SQL_SELECT *select;                //created in optimisation phase
++   TABLE	     *exec_tmp_table;        //used in 'exec' to hold temporary table
++   SELECT_LEX *select_lex;            //corresponding select_lex
++ 
++   my_bool test_function_query; // need to return select items 1 row
++   const char *zero_result_cause; // not 0 if exec must return zero result
++ 
++   JOIN(THD *thd, List<Item> &fields, 
++        ulong select_options, select_result *result):
++     join_tab(0),
++     table(0),
++     tables(0), const_tables(0),
++     sort_and_group(0), first_record(0),
++     do_send_rows(1),
++     send_records(0), found_records(0), examined_rows(0),
++     thd(thd),
++     sum_funcs(0),
++     having(0),
++     select_options(select_options),
++     result(result),
++     lock(thd->lock),
++     select_distinct(test(select_options & SELECT_DISTINCT)),
++     no_order(0), simple_order(0), simple_group(0), skip_sort_order(0),
++     need_tmp(0),
++     hidden_group_fields (0), /*safety*/
++     buffer_result(test(select_options & OPTION_BUFFER_RESULT) && 
++ 		  !test(select_options & OPTION_FOUND_ROWS)),
++     all_fields(fields),
++     fields_list(fields),
++     select(0),
++     exec_tmp_table(0),
++     select_lex(0), //for safety
++     test_function_query(0),
++     zero_result_cause(0)
++   {
++     fields_list = fields;
++     bzero((char*) &keyuse,sizeof(keyuse));
++     tmp_table_param.copy_field=0;
++     tmp_table_param.end_write_records= HA_POS_ERROR;
++   }
++ 
++   int prepare(TABLE_LIST *tables,
++ 	      COND *conds, ORDER *order, ORDER *group, Item *having,
++ 	      ORDER *proc_param, SELECT_LEX *select);
++   int optimize();
++   int global_optimize();
++   void exec();
++   int cleanup(THD *thd);
+  };
+  
+  
+***************
+*** 187,193 ****
+  bool store_val_in_field(Field *field,Item *val);
+  TABLE *create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
+  			ORDER *group, bool distinct, bool save_sum_fields,
+- 			bool allow_distinct_limit, ulong select_options);
+  void free_tmp_table(THD *thd, TABLE *entry);
+  void count_field_types(TMP_TABLE_PARAM *param, List<Item> &fields,
+  		       bool reset_with_sum_func);
+--- 249,256 ----
+  bool store_val_in_field(Field *field,Item *val);
+  TABLE *create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
+  			ORDER *group, bool distinct, bool save_sum_fields,
++ 			bool allow_distinct_limit, ulong select_options,
++ 			SELECT_LEX *first_select);
+  void free_tmp_table(THD *thd, TABLE *entry);
+  void count_field_types(TMP_TABLE_PARAM *param, List<Item> &fields,
+  		       bool reset_with_sum_func);

sql/sql_union.cc

@@ -40,17 +40,6 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
   DBUG_ENTER("mysql_union");
   st_select_lex_node * global;
 
-  /* Fix tables 'to-be-unioned-from' list to point at opened tables */
-  for (sl= &lex->select_lex;
-       sl;
-       sl= (SELECT_LEX *) sl->next)
-  {
-    for (TABLE_LIST *cursor= (TABLE_LIST *)sl->table_list.first;
-	 cursor;
-	 cursor=cursor->next)
-      cursor->table= cursor->table_list->table;
-  }
-
   /* Global option */
   if (((void*)(global= unit->global_parameters)) == ((void*)unit))
   {

sql/sql_yacc.yy

@@ -544,7 +544,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 	literal text_literal insert_ident order_ident
 	simple_ident select_item2 expr opt_expr opt_else sum_expr in_sum_expr
 	table_wild opt_pad no_in_expr expr_expr simple_expr no_and_expr
-	using_list
+	using_list subselect subselect_init
 
 %type <item_list>
 	expr_list udf_expr_list when_list ident_list ident_list_arg
@@ -612,7 +612,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 	table_to_table_list table_to_table opt_table_list opt_as
 	handler_rkey_function handler_read_or_scan
 	single_multi table_wild_list table_wild_one opt_wild union union_list
-	precision union_option
+	precision union_option subselect_start subselect_end
 END_OF_INPUT
 
 %type <NONE>
@@ -1547,8 +1547,8 @@ optional_braces:
 	| '(' ')' {}
 
 /* all possible expressions */
-expr:	expr_expr	{$$ = $1; }
-	| simple_expr	{$$ = $1; }
+expr:	expr_expr	{ $$= $1; }
+	| simple_expr	{ $$= $1; }
 
 /* expressions that begin with 'expr' */
 expr_expr:
@@ -1688,6 +1688,7 @@ simple_expr:
 	| NOT expr %prec NEG	{ $$= new Item_func_not($2); }
 	| '!' expr %prec NEG	{ $$= new Item_func_not($2); }
 	| '(' expr ')'		{ $$= $2; }
+	| subselect             { $$= $1; }
 	| '{' ident expr '}'	{ $$= $3; }
         | MATCH ident_list_arg AGAINST '(' expr ')'
           { Select->ftfunc_list.push_back((Item_func_match *)
@@ -3849,3 +3850,30 @@ optional_order_or_limit:
 union_option:
   /* empty */ {}
   | ALL {Lex->union_option=1;}
+
+subselect:
+  subselect_start subselect_init
+  subselect_end
+  {
+    $$= $2;
+  }
+
+subselect_init:
+  select_init
+  {
+    $$= new Item_subselect(current_thd, Lex->select);
+  }
+
+subselect_start:
+  '('
+  {
+    if (mysql_new_select(Lex, 1))
+      YYABORT;
+  }
+
+subselect_end:
+  ')'
+  {
+    LEX *lex=Lex;
+    lex->select = (SELECT_LEX*)lex->select->master->master;
+  }