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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 */
/*
UNION of select's
UNION's were introduced by Monty and Sinisa <sinisa@mysql.com>
*/
#include "mysql_priv.h"
#include "sql_select.h"
int mysql_union(THD *thd, LEX *lex,select_result *result)
{
SELECT_LEX *sl, *last_sl, *lex_sl;
ORDER *order;
List<Item> item_list;
TABLE *table;
int describe=(lex->select_lex.options & SELECT_DESCRIBE) ? 1 : 0;
int res;
bool found_rows_for_union= 0;
TABLE_LIST result_table_list;
TABLE_LIST *first_table=(TABLE_LIST *)lex->select_lex.table_list.first;
TMP_TABLE_PARAM tmp_table_param;
select_union *union_result;
DBUG_ENTER("mysql_union");
/* Fix tables 'to-be-unioned-from' list to point at opened tables */
last_sl= &lex->select_lex;
for (sl= last_sl;
sl && sl->linkage != NOT_A_SELECT;
last_sl=sl, sl=sl->next)
{
for (TABLE_LIST *cursor= (TABLE_LIST *)sl->table_list.first;
cursor;
cursor=cursor->next)
{
cursor->table= (my_reinterpret_cast(TABLE_LIST*) (cursor->table))->table;
}
}
/* last_sel now points at the last select where the ORDER BY is stored */
if (sl)
{
/*
The found SL is an extra SELECT_LEX argument that contains
the ORDER BY and LIMIT parameter for the whole UNION
*/
lex_sl= sl;
order= (ORDER *) lex_sl->order_list.first;
found_rows_for_union = (lex->select_lex.options & OPTION_FOUND_ROWS &&
!describe && sl->select_limit);
if (found_rows_for_union)
lex->select_lex.options ^= OPTION_FOUND_ROWS;
// This is done to eliminate unnecessary slowing down of the first query
if (!order || !describe)
last_sl->next=0; // Remove this extra element
}
else if (!last_sl->braces)
{
lex_sl= last_sl; // ORDER BY is here
order= (ORDER *) lex_sl->order_list.first;
}
else
{
lex_sl=0;
order=0;
}
if (describe)
{
Item *item;
item_list.push_back(new Item_empty_string("table",NAME_LEN));
item_list.push_back(new Item_empty_string("type",10));
item_list.push_back(item=new Item_empty_string("possible_keys",
NAME_LEN*MAX_KEY));
item->maybe_null=1;
item_list.push_back(item=new Item_empty_string("key",NAME_LEN));
item->maybe_null=1;
item_list.push_back(item=new Item_int("key_len",0,3));
item->maybe_null=1;
item_list.push_back(item=new Item_empty_string("ref",
NAME_LEN*MAX_REF_PARTS));
item->maybe_null=1;
item_list.push_back(new Item_real("rows",0.0,0,10));
item_list.push_back(new Item_empty_string("Extra",255));
}
else
{
Item *item;
List_iterator<Item> it(lex->select_lex.item_list);
TABLE_LIST *first_table= (TABLE_LIST*) lex->select_lex.table_list.first;
/* Create a list of items that will be in the result set */
while ((item= it++))
if (item_list.push_back(item))
DBUG_RETURN(-1);
if (setup_fields(thd,first_table,item_list,0,0,1))
DBUG_RETURN(-1);
}
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, !describe & !lex->union_option,
1, 0,
(lex->select_lex.options | thd->options |
TMP_TABLE_ALL_COLUMNS))))
DBUG_RETURN(-1);
table->file->extra(HA_EXTRA_WRITE_CACHE);
table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
bzero((char*) &result_table_list,sizeof(result_table_list));
result_table_list.db= (char*) "";
result_table_list.real_name=result_table_list.alias= (char*) "union";
result_table_list.table=table;
if (!(union_result=new select_union(table)))
{
res= -1;
goto exit;
}
union_result->not_describe= !describe;
union_result->tmp_table_param=&tmp_table_param;
for (sl= &lex->select_lex; sl; sl=sl->next)
{
lex->select=sl;
thd->offset_limit=sl->offset_limit;
thd->select_limit=sl->select_limit+sl->offset_limit;
if (thd->select_limit < sl->select_limit)
thd->select_limit= HA_POS_ERROR; // no limit
if (thd->select_limit == HA_POS_ERROR)
sl->options&= ~OPTION_FOUND_ROWS;
res=mysql_select(thd, (describe && sl->linkage==NOT_A_SELECT) ?
first_table : (TABLE_LIST*) sl->table_list.first,
sl->item_list,
sl->where,
(sl->braces) ? (ORDER *)sl->order_list.first :
(ORDER *) 0,
(ORDER*) sl->group_list.first,
sl->having,
(ORDER*) NULL,
sl->options | thd->options | SELECT_NO_UNLOCK |
((describe) ? SELECT_DESCRIBE : 0),
union_result);
if (res)
goto exit;
}
if (union_result->flush())
{
res= 1; // Error is already sent
goto exit;
}
delete union_result;
/* Send result to 'result' */
lex->select = &lex->select_lex;
res =-1;
{
/* Create a list of fields in the temporary table */
List_iterator<Item> it(item_list);
Field **field;
#if 0
List<Item_func_match> ftfunc_list;
ftfunc_list.empty();
#else
thd->lex.select_lex.ftfunc_list.empty();
#endif
for (field=table->field ; *field ; field++)
{
(void) it++;
(void) it.replace(new Item_field(*field));
}
if (!thd->fatal_error) // Check if EOM
{
if (lex_sl)
{
thd->offset_limit=lex_sl->offset_limit;
thd->select_limit=lex_sl->select_limit+lex_sl->offset_limit;
if (thd->select_limit < lex_sl->select_limit)
thd->select_limit= HA_POS_ERROR; // no limit
if (thd->select_limit == HA_POS_ERROR)
thd->options&= ~OPTION_FOUND_ROWS;
}
else
{
thd->offset_limit= 0;
thd->select_limit= thd->variables.select_limit;
}
if (describe)
thd->select_limit= HA_POS_ERROR; // no limit
res=mysql_select(thd,&result_table_list,
item_list, NULL, (describe) ? 0 : order,
(ORDER*) NULL, NULL, (ORDER*) NULL,
thd->options, result);
if (found_rows_for_union && !res)
thd->limit_found_rows = (ulonglong)table->file->records;
}
}
exit:
free_tmp_table(thd,table);
DBUG_RETURN(res);
}
/***************************************************************************
** store records in temporary table for UNION
***************************************************************************/
select_union::select_union(TABLE *table_par)
:table(table_par), not_describe(0)
{
bzero((char*) &info,sizeof(info));
/*
We can always use DUP_IGNORE because the temporary table will only
contain a unique key if we are using not using UNION ALL
*/
info.handle_duplicates=DUP_IGNORE;
}
select_union::~select_union()
{
}
int select_union::prepare(List<Item> &list)
{
if (not_describe && list.elements != table->fields)
{
my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
ER(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT),MYF(0));
return -1;
}
return 0;
}
bool select_union::send_data(List<Item> &values)
{
if (thd->offset_limit)
{ // using limit offset,count
thd->offset_limit--;
return 0;
}
fill_record(table->field,values);
if ((write_record(table,&info)))
{
if (create_myisam_from_heap(table, tmp_table_param, info.last_errno, 0))
return 1;
}
return 0;
}
bool select_union::send_eof()
{
return 0;
}
bool select_union::flush()
{
int error;
if ((error=table->file->extra(HA_EXTRA_NO_CACHE)))
{
table->file->print_error(error,MYF(0));
::send_error(&thd->net);
return 1;
}
return 0;
}
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