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/* 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)
- subselect in HAVING clause
- add subselect union select (sql_union.cc)
*/
#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):
assigned(0), executed(0), optimized(0), error(0)
{
DBUG_ENTER("Item_subselect::Item_subselect");
DBUG_PRINT("subs", ("select_lex 0x%xl", (long) select_lex));
result= new select_subselect(this);
SELECT_LEX_UNIT *unit= select_lex->master_unit();
unit->offset_limit_cnt= unit->global_parameters->offset_limit;
unit->select_limit_cnt= unit->global_parameters->select_limit+
unit->global_parameters ->offset_limit;
if (unit->select_limit_cnt < unit->global_parameters->select_limit)
unit->select_limit_cnt= HA_POS_ERROR; // no limit
if (unit->select_limit_cnt == HA_POS_ERROR)
select_lex->options&= ~OPTION_FOUND_ROWS;
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)
{
if (thd->having_fix_field)
{
//TODO: subselects in having do not suported now
my_printf_error(ER_SYNTAX_ERROR, ER(ER_SYNTAX_ERROR), MYF(0));
return 1;
}
// 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->master_unit()))
return 1;
thd->lex.select= save_select;
return 0;
}
int Item_subselect::exec()
{
if (!optimized)
{
optimized=1;
if (join->optimize())
{
executed= 1;
return (join->error?join->error:1);
}
}
if (join->select_lex->depended && executed)
{
if (join->reinit())
{
error= 1;
return 1;
}
assign_null();
executed= assigned= 0;
}
if (!executed)
{
SELECT_LEX *save_select= join->thd->lex.select;
join->thd->lex.select= select_lex;
join->exec();
join->thd->lex.select= save_select;
executed= 1;
return join->error;
}
return 0;
}
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