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EXISTS(SELECT * ...)

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close table before opening in optimize
This commit is contained in:
bell@sanja.is.com.ua 2004-06-10 21:33:15 +03:00
parent 5f235eb828
commit be642b9bcd
4 changed files with 39 additions and 4 deletions
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18
mysql-test/r/subselect.result
View file

@ -328,10 +328,10 @@ patient_uq clinic_uq
explain extended select * from t6 where exists (select * from t7 where uq = clinic_uq);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t6 ALL NULL NULL NULL NULL 4 Using where
2 DEPENDENT SUBQUERY t7 eq_ref PRIMARY PRIMARY 4 test.t6.clinic_uq 1
2 DEPENDENT SUBQUERY t7 eq_ref PRIMARY PRIMARY 4 test.t6.clinic_uq 1 Using index
Warnings:
Note 1276 Field or reference 'clinic_uq' of SELECT #2 was resolved in SELECT #1
Note 1003 select test.t6.patient_uq AS `patient_uq`,test.t6.clinic_uq AS `clinic_uq` from test.t6 where exists(select test.t7.uq AS `uq`,test.t7.name AS `name` from test.t7 where (test.t7.uq = test.t6.clinic_uq))
Note 1003 select test.t6.patient_uq AS `patient_uq`,test.t6.clinic_uq AS `clinic_uq` from test.t6 where exists(select 1 AS `Not_used` from test.t7 where (test.t7.uq = test.t6.clinic_uq))
select * from t1 where a= (select a from t2,t4 where t2.b=t4.b);
ERROR 23000: Column: 'a' in field list is ambiguous
drop table t1,t2,t3;
@ -1817,3 +1817,17 @@ a
1
3
DROP TABLE t1;
create table t1 (a int, b int);
insert into t1 values (1,2),(3,4);
select * from t1 up where exists (select * from t1 where t1.a=up.a);
a b
1 2
3 4
explain extended select * from t1 up where exists (select * from t1 where t1.a=up.a);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY up ALL NULL NULL NULL NULL 2 Using where
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
Warnings:
Note 1276 Field or reference 'up.a' of SELECT #2 was resolved in SELECT #1
Note 1003 select test.up.a AS `a`,test.up.b AS `b` from test.t1 up where exists(select 1 AS `Not_used` from test.t1 where (test.t1.a = test.up.a))
drop table t1;

9
mysql-test/t/subselect.test
View file

@ -1158,3 +1158,12 @@ SELECT a FROM t1 WHERE a >= ALL ( SELECT a FROM t1 WHERE b = 2 );
SELECT a FROM t1 WHERE a <= ALL ( SELECT a FROM t1 WHERE b = 2 );
SELECT a FROM t1 WHERE a <> ALL ( SELECT a FROM t1 WHERE b = 2 );
DROP TABLE t1;
#
# SELECT(EXISTS * ...)optimisation
#
create table t1 (a int, b int);
insert into t1 values (1,2),(3,4);
select * from t1 up where exists (select * from t1 where t1.a=up.a);
explain extended select * from t1 up where exists (select * from t1 where t1.a=up.a);
drop table t1;

15
sql/sql_base.cc
View file

@ -2184,8 +2184,19 @@ int setup_wild(THD *thd, TABLE_LIST *tables, List<Item> &fields,
!((Item_field*) item)->field)
{
uint elem= fields.elements;
if (insert_fields(thd,tables,((Item_field*) item)->db_name,
((Item_field*) item)->table_name, &it))
Item_subselect *subsel= thd->lex->current_select->master_unit()->item;
if (subsel &&
subsel->substype() == Item_subselect::EXISTS_SUBS)
{
/*
It is EXISTS(SELECT * ...) and we can replace * by any constant.
Item_int do not need fix_fields() because it is basic constant.
*/
it.replace(new Item_int("Not_used", (longlong) 1, 21));
}
else if (insert_fields(thd,tables,((Item_field*) item)->db_name,
((Item_field*) item)->table_name, &it))
{
if (stmt)
thd->restore_backup_item_arena(stmt, &backup);

1
sql/sql_table.cc
View file

@ -1861,6 +1861,7 @@ send_result_message:
TABLE_LIST *save_next= table->next;
table->next= 0;
result_code= mysql_recreate_table(thd, table, 0);
close_thread_tables(thd);
if (!result_code) // recreation went ok
{
if ((table->table= open_ltable(thd, table, lock_type)) &&