set @save_optimizer_switch=@@optimizer_switch; set @@optimizer_switch='optimize_join_buffer_size=on'; set @@optimizer_switch='semijoin_with_cache=on'; set @@optimizer_switch='outer_join_with_cache=on'; set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on'; set join_cache_level=6; show variables like 'join_cache_level'; Variable_name Value join_cache_level 6 set @join_cache_level_for_subselect3_test=@@join_cache_level; drop table if exists t0, t1, t2, t3, t4, t5, t11, t12, t21, t22; set @subselect3_tmp= @@optimizer_switch; set optimizer_switch='semijoin=on,firstmatch=on,loosescan=on,semijoin_with_cache=on'; set join_cache_level=@join_cache_level_for_subselect3_test; create table t1 (oref int, grp int, ie int) ; insert into t1 (oref, grp, ie) values (1, 1, 1), (1, 1, 1), (1, 2, NULL), (2, 1, 3), (3, 1, 4), (3, 2, NULL); create table t2 (oref int, a int); insert into t2 values (1, 1), (2, 2), (3, 3), (4, NULL), (2, NULL); select a, oref, a in (select max(ie) from t1 where oref=t2.oref group by grp) Z from t2; a oref Z 1 1 1 2 2 0 3 3 NULL NULL 4 0 NULL 2 NULL explain extended select a, oref, a in (select max(ie) from t1 where oref=t2.oref group by grp) Z from t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 5 100.00 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 100.00 Using where; Using temporary Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref`,<`test`.`t2`.`a`,`test`.`t2`.`oref`>((`test`.`t2`.`a`,(/* select#2 */ select max(`test`.`t1`.`ie`) from `test`.`t1` where `test`.`t1`.`oref` = `test`.`t2`.`oref` group by `test`.`t1`.`grp` having trigcond((`test`.`t2`.`a`) = (max(`test`.`t1`.`ie`)))))) AS `Z` from `test`.`t2` explain extended select a, oref from t2 where a in (select max(ie) from t1 where oref=t2.oref group by grp); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 5 100.00 Using where 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 100.00 Using where; Using temporary Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref` from `test`.`t2` where <`test`.`t2`.`a`,`test`.`t2`.`oref`>((`test`.`t2`.`a`,(/* select#2 */ select max(`test`.`t1`.`ie`) from `test`.`t1` where `test`.`t1`.`oref` = `test`.`t2`.`oref` group by `test`.`t1`.`grp` having (`test`.`t2`.`a`) = (max(`test`.`t1`.`ie`))))) select a, oref, a in ( select max(ie) from t1 where oref=t2.oref group by grp union select max(ie) from t1 where oref=t2.oref group by grp ) Z from t2; a oref Z 1 1 1 2 2 0 3 3 NULL NULL 4 0 NULL 2 NULL create table t3 (a int); insert into t3 values (NULL), (NULL); flush status; select a in (select max(ie) from t1 where oref=4 group by grp) from t3; a in (select max(ie) from t1 where oref=4 group by grp) 0 0 show status like 'Handler_read_rnd_next'; Variable_name Value Handler_read_rnd_next 11 select ' ^ This must show 11' Z; Z ^ This must show 11 set @save_optimizer_switch=@@optimizer_switch; set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 2 100.00 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 100.00 Using where; Using temporary Warnings: Note 1003 /* select#1 */ select <`test`.`t3`.`a`>((`test`.`t3`.`a`,(/* select#2 */ select max(`test`.`t1`.`ie`) from `test`.`t1` where `test`.`t1`.`oref` = 4 group by `test`.`t1`.`grp` having trigcond((`test`.`t3`.`a`) = (max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3` set @@optimizer_switch=@save_optimizer_switch; drop table t1, t2, t3; create table t1 (a int, oref int, key(a)); insert into t1 values (1, 1), (1, NULL), (2, 3), (2, NULL), (3, NULL); insert into t1 values (5, 7), (8, 9), (4, 1); create table t2 (a int, oref int); insert into t2 values (1, 1), (2,2), (NULL, 3), (NULL, 4); select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2; oref a Z 1 1 1 2 2 0 3 NULL NULL 4 NULL 0 explain extended select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 4 100.00 2 DEPENDENT SUBQUERY t1 index_subquery a a 5 func 2 100.00 Using where; Full scan on NULL key Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`oref` AS `oref`,`test`.`t2`.`a` AS `a`,<`test`.`t2`.`a`,`test`.`t2`.`oref`>((`test`.`t2`.`a`,(((`test`.`t2`.`a`) in t1 on a checking NULL where `test`.`t1`.`oref` = `test`.`t2`.`oref` having trigcond(`test`.`t1`.`a` is null))))) AS `Z` from `test`.`t2` flush status; select oref, a from t2 where a in (select a from t1 where oref=t2.oref); oref a 1 1 show status like '%Handler_read_rnd_next'; Variable_name Value Handler_read_rnd_next 5 delete from t2; insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0); set optimizer_switch='subquery_cache=off'; flush status; select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2; oref a Z 0 NULL 0 0 NULL 0 0 NULL 0 0 NULL 0 show status like '%Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_last 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_retry 0 Handler_read_rnd 0 Handler_read_rnd_deleted 0 Handler_read_rnd_next 41 select 'No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.' Z; Z No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1. set @@optimizer_switch=@save_optimizer_switch; drop table t1, t2; create table t1 (a int, b int, primary key (a)); insert into t1 values (1,1), (3,1),(100,1); create table t2 (a int, b int); insert into t2 values (1,1),(2,1),(NULL,1),(NULL,0); select a,b, a in (select a from t1 where t1.b = t2.b) Z from t2 ; a b Z 1 1 1 2 1 0 NULL 1 NULL NULL 0 0 drop table t1, t2; create table t1 (a int, b int, key(a)); insert into t1 values (0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9); create table t2 like t1; insert into t2 select * from t1; update t2 set b=1; create table t3 (a int, oref int); insert into t3 values (1, 1), (NULL,1), (NULL,0); select a, oref, t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z from t3; a oref Z 1 1 1 NULL 1 NULL NULL 0 0 explain extended select a, oref, t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z from t3; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 3 100.00 2 DEPENDENT SUBQUERY t1 ref_or_null a a 5 func 4 100.00 Using where; Full scan on NULL key 2 DEPENDENT SUBQUERY t2 ref a a 5 test.t1.b 1 100.00 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan Warnings: Note 1276 Field or reference 'test.t3.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<`test`.`t3`.`a`,`test`.`t3`.`oref`>((`test`.`t3`.`a`,(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`b` = `test`.`t3`.`oref` and trigcond((`test`.`t3`.`a`) = `test`.`t1`.`a` or `test`.`t1`.`a` is null) and `test`.`t2`.`a` = `test`.`t1`.`b` having trigcond(`test`.`t1`.`a` is null)))) AS `Z` from `test`.`t3` drop table t1, t2, t3; create table t1 (a int NOT NULL, b int NOT NULL, key(a)); insert into t1 values (0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9); create table t2 like t1; insert into t2 select * from t1; update t2 set b=1; create table t3 (a int, oref int); insert into t3 values (1, 1), (NULL,1), (NULL,0); select a, oref, t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z from t3; a oref Z 1 1 1 NULL 1 NULL NULL 0 0 This must show a trig_cond: explain extended select a, oref, t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z from t3; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 3 100.00 2 DEPENDENT SUBQUERY t1 ref a a 4 func 2 100.00 Using where; Full scan on NULL key 2 DEPENDENT SUBQUERY t2 ref a a 4 test.t1.b 1 100.00 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan Warnings: Note 1276 Field or reference 'test.t3.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<`test`.`t3`.`a`,`test`.`t3`.`oref`>((`test`.`t3`.`a`,(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`b` = `test`.`t3`.`oref` and trigcond((`test`.`t3`.`a`) = `test`.`t1`.`a`) and `test`.`t2`.`a` = `test`.`t1`.`b`))) AS `Z` from `test`.`t3` drop table t1,t2,t3; create table t1 (oref int, grp int); insert into t1 (oref, grp) values (1, 1), (1, 1); create table t2 (oref int, a int); insert into t2 values (1, NULL), (2, NULL); select a, oref, a in (select count(*) from t1 group by grp having grp=t2.oref) Z from t2; a oref Z NULL 1 NULL NULL 2 0 This must show a trig_cond: explain extended select a, oref, a in (select count(*) from t1 group by grp having grp=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary Warnings: Note 1276 Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref`,<`test`.`t2`.`a`,`test`.`t2`.`oref`>((`test`.`t2`.`a`,(/* select#2 */ select count(0) from `test`.`t1` group by `test`.`t1`.`grp` having `test`.`t1`.`grp` = `test`.`t2`.`oref` and trigcond((`test`.`t2`.`a`) = (count(0)))))) AS `Z` from `test`.`t2` drop table t1, t2; create table t1 (a int, b int, primary key (a)); insert into t1 values (1,1), (3,1),(100,1); create table t2 (a int, b int); insert into t2 values (1,1),(2,1),(NULL,1),(NULL,0); select a,b, a in (select a from t1 where t1.b = t2.b union select a from t1 where t1.b = t2.b) Z from t2 ; a b Z 1 1 1 2 1 0 NULL 1 NULL NULL 0 0 select a,b, a in (select a from t1 where t1.b = t2.b) Z from t2 ; a b Z 1 1 1 2 1 0 NULL 1 NULL NULL 0 0 drop table t1, t2; create table t3 (a int); insert into t3 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t2 (a int, b int, oref int); insert into t2 values (NULL,1, 100), (NULL,2, 100); create table t1 (a int, b int, c int, key(a,b)); insert into t1 select 2*A, 2*A, 100 from t3; explain extended select a,b, oref, (a,b) in (select a,b from t1 where c=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 2 DEPENDENT SUBQUERY t1 index_subquery a a 5 func 2 100.00 Using where; Full scan on NULL key Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`oref` AS `oref`,<`test`.`t2`.`a`,`test`.`t2`.`b`,`test`.`t2`.`oref`>(((`test`.`t2`.`a`,`test`.`t2`.`b`),(((`test`.`t2`.`a`) in t1 on a checking NULL where `test`.`t1`.`c` = `test`.`t2`.`oref` and trigcond(trigcond((`test`.`t2`.`a`) = `test`.`t1`.`a` or `test`.`t1`.`a` is null)) and trigcond(trigcond((`test`.`t2`.`b`) = `test`.`t1`.`b` or `test`.`t1`.`b` is null)) having trigcond(`test`.`t1`.`a` is null) and trigcond(`test`.`t1`.`b` is null))))) AS `Z` from `test`.`t2` select a,b, oref, (a,b) in (select a,b from t1 where c=t2.oref) Z from t2; a b oref Z NULL 1 100 0 NULL 2 100 NULL create table t4 (x int); insert into t4 select A.a + 10*B.a from t1 A, t1 B; explain extended select a,b, oref, (a,b) in (select a,b from t1,t4 where c=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 2 DEPENDENT SUBQUERY t1 ref_or_null a a 5 func 2 100.00 Using where; Full scan on NULL key 2 DEPENDENT SUBQUERY t4 ALL NULL NULL NULL NULL 100 100.00 Using join buffer (flat, BNL join) Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`oref` AS `oref`,<`test`.`t2`.`a`,`test`.`t2`.`b`,`test`.`t2`.`oref`>(((`test`.`t2`.`a`,`test`.`t2`.`b`),(/* select#2 */ select `test`.`t1`.`a`,`test`.`t1`.`b` from `test`.`t1` join `test`.`t4` where `test`.`t1`.`c` = `test`.`t2`.`oref` and trigcond(trigcond((`test`.`t2`.`a`) = `test`.`t1`.`a` or `test`.`t1`.`a` is null)) and trigcond(trigcond((`test`.`t2`.`b`) = `test`.`t1`.`b` or `test`.`t1`.`b` is null)) having trigcond(`test`.`t1`.`a` is null) and trigcond(`test`.`t1`.`b` is null)))) AS `Z` from `test`.`t2` select a,b, oref, (a,b) in (select a,b from t1,t4 where c=t2.oref) Z from t2; a b oref Z NULL 1 100 0 NULL 2 100 NULL drop table t1,t2,t3,t4; create table t1 (oref char(4), grp int, ie1 int, ie2 int); insert into t1 (oref, grp, ie1, ie2) values ('aa', 10, 2, 1), ('aa', 10, 1, 1), ('aa', 20, 2, 1), ('bb', 10, 3, 1), ('cc', 10, 4, 2), ('cc', 20, 3, 2), ('ee', 10, 2, 1), ('ee', 10, 1, 2), ('ff', 20, 2, 2), ('ff', 20, 1, 2); create table t2 (oref char(4), a int, b int); insert into t2 values ('ee', NULL, 1), ('bb', 2, 1), ('ff', 2, 2), ('cc', 3, NULL), ('bb', NULL, NULL), ('aa', 1, 1), ('dd', 1, NULL); alter table t1 add index idx(ie1,ie2); select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2 where a=3 and b is null ; oref a b Z cc 3 NULL NULL insert into t2 values ('new1', 10,10); insert into t1 values ('new1', 1234, 10, NULL); select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2 where a=10 and b=10; oref a b Z new1 10 10 NULL explain extended select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2 where a=10 and b=10; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 8 100.00 Using where 2 DEPENDENT SUBQUERY t1 index_subquery idx idx 5 func 4 100.00 Using where; Full scan on NULL key Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`oref` AS `oref`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,<`test`.`t2`.`a`,`test`.`t2`.`b`,`test`.`t2`.`oref`>(((`test`.`t2`.`a`,`test`.`t2`.`b`),(((`test`.`t2`.`a`) in t1 on idx checking NULL where `test`.`t1`.`oref` = `test`.`t2`.`oref` and trigcond(trigcond((`test`.`t2`.`a`) = `test`.`t1`.`ie1` or `test`.`t1`.`ie1` is null)) and trigcond(trigcond((`test`.`t2`.`b`) = `test`.`t1`.`ie2` or `test`.`t1`.`ie2` is null)) having trigcond(`test`.`t1`.`ie1` is null) and trigcond(`test`.`t1`.`ie2` is null))))) AS `Z` from `test`.`t2` where `test`.`t2`.`a` = 10 and `test`.`t2`.`b` = 10 drop table t1, t2; create table t1 (oref char(4), grp int, ie int); insert into t1 (oref, grp, ie) values ('aa', 10, 2), ('aa', 10, 1), ('aa', 20, NULL), ('bb', 10, 3), ('cc', 10, 4), ('cc', 20, NULL), ('ee', 10, NULL), ('ee', 10, NULL), ('ff', 20, 2), ('ff', 20, 1); create table t2 (oref char(4), a int); insert into t2 values ('ee', NULL), ('bb', 2), ('ff', 2), ('cc', 3), ('aa', 1), ('dd', NULL), ('bb', NULL); select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; oref a Z ee NULL NULL bb 2 0 ff 2 1 cc 3 NULL aa 1 1 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select ie from t1 where oref=t2.oref); oref a aa 1 ff 2 select oref, a from t2 where a not in (select ie from t1 where oref=t2.oref); oref a bb 2 dd NULL select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp) Z from t2; oref a Z ee NULL NULL bb 2 0 ff 2 0 cc 3 NULL aa 1 1 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select min(ie) from t1 where oref=t2.oref group by grp); oref a aa 1 select oref, a from t2 where a not in (select min(ie) from t1 where oref=t2.oref group by grp); oref a bb 2 ff 2 dd NULL update t1 set ie=3 where oref='ff' and ie=1; select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp) Z from t2; oref a Z ee NULL NULL bb 2 0 ff 2 1 cc 3 NULL aa 1 1 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select min(ie) from t1 where oref=t2.oref group by grp); oref a ff 2 aa 1 select oref, a from t2 where a not in (select min(ie) from t1 where oref=t2.oref group by grp); oref a bb 2 dd NULL select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1) Z from t2; oref a Z ee NULL 0 bb 2 0 ff 2 1 cc 3 0 aa 1 0 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1); oref a ff 2 select oref, a from t2 where a not in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1); oref a ee NULL bb 2 cc 3 aa 1 dd NULL alter table t1 add index idx(ie); explain select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 2 DEPENDENT SUBQUERY t1 index_subquery idx idx 5 func 4 Using where; Full scan on NULL key select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; oref a Z ee NULL NULL bb 2 0 ff 2 1 cc 3 NULL aa 1 1 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select ie from t1 where oref=t2.oref); oref a aa 1 ff 2 select oref, a from t2 where a not in (select ie from t1 where oref=t2.oref); oref a bb 2 dd NULL alter table t1 drop index idx; alter table t1 add index idx(oref,ie); explain select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 2 DEPENDENT SUBQUERY t1 ref_or_null idx idx 10 test.t2.oref,func 4 Using where; Using index; Full scan on NULL key select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; oref a Z ee NULL NULL bb 2 0 ff 2 1 cc 3 NULL aa 1 1 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select ie from t1 where oref=t2.oref); oref a ff 2 aa 1 select oref, a from t2 where a not in (select ie from t1 where oref=t2.oref); oref a bb 2 dd NULL explain select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1) Z from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 2 DEPENDENT SUBQUERY t1 ref idx idx 5 test.t2.oref 2 Using where; Using temporary select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1) Z from t2; oref a Z ee NULL 0 bb 2 0 ff 2 1 cc 3 0 aa 1 0 dd NULL 0 bb NULL NULL select oref, a from t2 where a in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1); oref a ff 2 select oref, a from t2 where a not in (select min(ie) from t1 where oref=t2.oref group by grp having min(ie) > 1); oref a ee NULL bb 2 cc 3 aa 1 dd NULL drop table t1,t2; create table t1 (oref char(4), grp int, ie1 int, ie2 int); insert into t1 (oref, grp, ie1, ie2) values ('aa', 10, 2, 1), ('aa', 10, 1, 1), ('aa', 20, 2, 1), ('bb', 10, 3, 1), ('cc', 10, 4, 2), ('cc', 20, 3, 2), ('ee', 10, 2, 1), ('ee', 10, 1, 2), ('ff', 20, 2, 2), ('ff', 20, 1, 2); create table t2 (oref char(4), a int, b int); insert into t2 values ('ee', NULL, 1), ('bb', 2, 1), ('ff', 2, 2), ('cc', 3, NULL), ('bb', NULL, NULL), ('aa', 1, 1), ('dd', 1, NULL); select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2; oref a b Z ee NULL 1 NULL bb 2 1 0 ff 2 2 1 cc 3 NULL NULL bb NULL NULL NULL aa 1 1 1 dd 1 NULL 0 select oref, a, b from t2 where (a,b) in (select ie1,ie2 from t1 where oref=t2.oref); oref a b aa 1 1 ff 2 2 select oref, a, b from t2 where (a,b) not in (select ie1,ie2 from t1 where oref=t2.oref); oref a b bb 2 1 dd 1 NULL select oref, a, b, (a,b) in (select min(ie1),max(ie2) from t1 where oref=t2.oref group by grp) Z from t2; oref a b Z ee NULL 1 0 bb 2 1 0 ff 2 2 0 cc 3 NULL NULL bb NULL NULL NULL aa 1 1 1 dd 1 NULL 0 select oref, a, b from t2 where (a,b) in (select min(ie1), max(ie2) from t1 where oref=t2.oref group by grp); oref a b aa 1 1 select oref, a, b from t2 where (a,b) not in (select min(ie1), max(ie2) from t1 where oref=t2.oref group by grp); oref a b ee NULL 1 bb 2 1 ff 2 2 dd 1 NULL alter table t1 add index idx(ie1,ie2); explain select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 2 DEPENDENT SUBQUERY t1 index_subquery idx idx 5 func 4 Using where; Full scan on NULL key select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2; oref a b Z ee NULL 1 NULL bb 2 1 0 ff 2 2 1 cc 3 NULL NULL bb NULL NULL NULL aa 1 1 1 dd 1 NULL 0 select oref, a, b from t2 where (a,b) in (select ie1,ie2 from t1 where oref=t2.oref); oref a b aa 1 1 ff 2 2 select oref, a, b from t2 where (a,b) not in (select ie1,ie2 from t1 where oref=t2.oref); oref a b bb 2 1 dd 1 NULL explain extended select oref, a, b, (a,b) in (select ie1,ie2 from t1 where oref=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 100.00 2 DEPENDENT SUBQUERY t1 index_subquery idx idx 5 func 4 100.00 Using where; Full scan on NULL key Warnings: Note 1276 Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`oref` AS `oref`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,<`test`.`t2`.`a`,`test`.`t2`.`b`,`test`.`t2`.`oref`>(((`test`.`t2`.`a`,`test`.`t2`.`b`),(((`test`.`t2`.`a`) in t1 on idx checking NULL where `test`.`t1`.`oref` = `test`.`t2`.`oref` and trigcond(trigcond((`test`.`t2`.`a`) = `test`.`t1`.`ie1` or `test`.`t1`.`ie1` is null)) and trigcond(trigcond((`test`.`t2`.`b`) = `test`.`t1`.`ie2` or `test`.`t1`.`ie2` is null)) having trigcond(`test`.`t1`.`ie1` is null) and trigcond(`test`.`t1`.`ie2` is null))))) AS `Z` from `test`.`t2` drop table t1,t2; create table t1 (oref char(4), grp int, ie int primary key); insert into t1 (oref, grp, ie) values ('aa', 10, 2), ('aa', 10, 1), ('bb', 10, 3), ('cc', 10, 4), ('cc', 20, 5), ('cc', 10, 6); create table t2 (oref char(4), a int); insert into t2 values ('ee', NULL), ('bb', 2), ('cc', 5), ('cc', 2), ('cc', NULL), ('aa', 1), ('bb', NULL); explain select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 2 DEPENDENT SUBQUERY t1 unique_subquery PRIMARY PRIMARY 4 func 1 Using where; Full scan on NULL key select oref, a, a in (select ie from t1 where oref=t2.oref) Z from t2; oref a Z ee NULL 0 bb 2 0 cc 5 1 cc 2 0 cc NULL NULL aa 1 1 bb NULL NULL select oref, a from t2 where a in (select ie from t1 where oref=t2.oref); oref a aa 1 cc 5 select oref, a from t2 where a not in (select ie from t1 where oref=t2.oref); oref a ee NULL bb 2 cc 2 explain select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp) Z from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 7 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6 Using where; Using temporary select oref, a, a in (select min(ie) from t1 where oref=t2.oref group by grp) Z from t2; oref a Z ee NULL 0 bb 2 0 cc 5 1 cc 2 0 cc NULL NULL aa 1 1 bb NULL NULL drop table t1,t2; create table t1 (a int, b int); insert into t1 values (0,0), (2,2), (3,3); create table t2 (a int, b int); insert into t2 values (1,1), (3,3); select a, b, (a,b) in (select a, min(b) from t2 group by a) Z from t1; a b Z 0 0 0 2 2 0 3 3 1 insert into t2 values (NULL,4); select a, b, (a,b) in (select a, min(b) from t2 group by a) Z from t1; a b Z 0 0 0 2 2 0 3 3 1 drop table t1,t2; CREATE TABLE t1 (a int, b INT, c CHAR(10) NOT NULL, PRIMARY KEY (a, b)); INSERT INTO t1 VALUES (1,1,'a'), (1,2,'b'), (1,3,'c'), (1,4,'d'), (1,5,'e'), (2,1,'f'), (2,2,'g'), (2,3,'h'), (3,4,'i'),(3,3,'j'), (3,2,'k'), (3,1,'l'), (1,9,'m'); CREATE TABLE t2 (a int, b INT, c CHAR(10) NOT NULL, PRIMARY KEY (a, b)); INSERT INTO t2 SELECT * FROM t1; SELECT a, MAX(b), (SELECT t.c FROM t1 AS t WHERE t1.a=t.a AND t.b=MAX(t1.b)) as test FROM t1 GROUP BY a; a MAX(b) test 1 9 m 2 3 h 3 4 i SELECT * FROM t1 GROUP by t1.a HAVING (MAX(t1.b) > (SELECT MAX(t2.b) FROM t2 WHERE t2.c < t1.c HAVING MAX(t2.b+t1.a) < 10)); a b c SELECT a,b,c FROM t1 WHERE b in (9,3,4) ORDER BY b,c; a b c 1 3 c 2 3 h 3 3 j 1 4 d 3 4 i 1 9 m SELECT a, MAX(b), (SELECT COUNT(DISTINCT t.c) FROM t1 AS t WHERE t1.a=t.a AND t.b=MAX(t1.b) LIMIT 1) as cnt, (SELECT t.b FROM t1 AS t WHERE t1.a=t.a AND t.b=MAX(t1.b) LIMIT 1) as t_b, (SELECT t.c FROM t1 AS t WHERE t1.a=t.a AND t.b=MAX(t1.b) LIMIT 1) as t_b, (SELECT t.c FROM t1 AS t WHERE t1.a=t.a AND t.b=MAX(t1.b) ORDER BY t.c LIMIT 1) as t_b FROM t1 GROUP BY a; a MAX(b) cnt t_b t_b t_b 1 9 1 9 m m 2 3 1 3 h h 3 4 1 4 i i SELECT a, MAX(b), (SELECT t.c FROM t1 AS t WHERE t1.a=t.a AND t.b=MAX(t1.b) LIMIT 1) as test FROM t1 GROUP BY a; a MAX(b) test 1 9 m 2 3 h 3 4 i DROP TABLE t1, t2; set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off"; CREATE TABLE t1 (a int); CREATE TABLE t2 (b int, PRIMARY KEY(b)); INSERT INTO t1 VALUES (1), (NULL), (4); INSERT INTO t2 VALUES (3), (1),(2), (5), (4), (7), (6); EXPLAIN EXTENDED SELECT a FROM t1, t2 WHERE a=b AND (b NOT IN (SELECT a FROM t1)); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where 1 PRIMARY t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 100.00 Using index 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 3 100.00 Using where Warnings: Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`b` = `test`.`t1`.`a` and !<`test`.`t1`.`a`>((`test`.`t1`.`a`,(/* select#2 */ select `test`.`t1`.`a` from `test`.`t1` where trigcond((`test`.`t2`.`b`) = `test`.`t1`.`a` or `test`.`t1`.`a` is null) having trigcond(`test`.`t1`.`a` is null)))) SELECT a FROM t1, t2 WHERE a=b AND (b NOT IN (SELECT a FROM t1)); a SELECT a FROM t1, t2 WHERE a=b AND (b NOT IN (SELECT a FROM t1 WHERE a > 4)); a 1 4 DROP TABLE t1,t2; CREATE TABLE t1 (id int); CREATE TABLE t2 (id int PRIMARY KEY); CREATE TABLE t3 (id int PRIMARY KEY, name varchar(10)); INSERT INTO t1 VALUES (2), (NULL), (3), (1); INSERT INTO t2 VALUES (234), (345), (457); INSERT INTO t3 VALUES (222,'bbb'), (333,'ccc'), (111,'aaa'); EXPLAIN SELECT * FROM t1 WHERE t1.id NOT IN (SELECT t2.id FROM t2,t3 WHERE t3.name='xxx' AND t2.id=t3.id); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where 2 DEPENDENT SUBQUERY t2 eq_ref PRIMARY PRIMARY 4 func 1 Using where; Using index; Full scan on NULL key 2 DEPENDENT SUBQUERY t3 eq_ref PRIMARY PRIMARY 4 test.t2.id 1 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan SELECT * FROM t1 WHERE t1.id NOT IN (SELECT t2.id FROM t2,t3 WHERE t3.name='xxx' AND t2.id=t3.id); id 2 NULL 3 1 SELECT (t1.id IN (SELECT t2.id FROM t2,t3 WHERE t3.name='xxx' AND t2.id=t3.id)) AS x FROM t1; x 0 0 0 0 DROP TABLE t1,t2,t3; CREATE TABLE t1 (a INT NOT NULL); INSERT INTO t1 VALUES (1),(-1), (65),(66); CREATE TABLE t2 (a INT UNSIGNED NOT NULL PRIMARY KEY); INSERT INTO t2 VALUES (65),(66); SELECT a FROM t1 WHERE a NOT IN (65,66); a 1 -1 SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2); a 1 -1 EXPLAIN SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where 2 DEPENDENT SUBQUERY t2 unique_subquery PRIMARY PRIMARY 4 func 1 Using index; Using where DROP TABLE t1, t2; set @@optimizer_switch=@save_optimizer_switch; CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES(1); CREATE TABLE t2 (placeholder CHAR(11)); INSERT INTO t2 VALUES("placeholder"); SELECT ROW(1, 2) IN (SELECT t1.a, 2) FROM t1 GROUP BY t1.a; ROW(1, 2) IN (SELECT t1.a, 2) 1 SELECT ROW(1, 2) IN (SELECT t1.a, 2 FROM t2) FROM t1 GROUP BY t1.a; ROW(1, 2) IN (SELECT t1.a, 2 FROM t2) 1 DROP TABLE t1, t2; CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (1),(2),(3); CREATE TABLE t2 SELECT * FROM t1; SELECT 1 FROM t1 WHERE t1.a NOT IN (SELECT 1 FROM t1, t2 WHERE 0); 1 1 1 1 DROP TABLE t1, t2; create table t1 (a int, b decimal(13, 3)); insert into t1 values (1, 0.123); select a, (select max(b) from t1) into outfile "subselect.out.file.1" from t1; delete from t1; load data infile "subselect.out.file.1" into table t1; select * from t1; a b 1 0.123 drop table t1; CREATE TABLE t1 ( pk INT PRIMARY KEY, int_key INT, varchar_key VARCHAR(5) UNIQUE, varchar_nokey VARCHAR(5) ); INSERT INTO t1 VALUES (9, 7,NULL,NULL), (10,8,'p' ,'p'); SELECT varchar_nokey FROM t1 WHERE NULL NOT IN ( SELECT INNR.pk FROM t1 AS INNR2 LEFT JOIN t1 AS INNR ON ( INNR2.int_key = INNR.int_key ) WHERE INNR.varchar_key > 'n{' ); varchar_nokey DROP TABLE t1; CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (1), (2), (11); # 2nd and 3rd columns should be same SELECT a, ROW(11, 12) = (SELECT a, 22), ROW(11, 12) IN (SELECT a, 22) FROM t1 GROUP BY t1.a; a ROW(11, 12) = (SELECT a, 22) ROW(11, 12) IN (SELECT a, 22) 1 0 0 2 0 0 11 0 0 SELECT a, ROW(11, 12) = (SELECT a, 12), ROW(11, 12) IN (SELECT a, 12) FROM t1 GROUP BY t1.a; a ROW(11, 12) = (SELECT a, 12) ROW(11, 12) IN (SELECT a, 12) 1 0 0 2 0 0 11 1 1 SELECT a, ROW(11, 12) = (SELECT a, 22), ROW(11, 12) IN (SELECT a, 22) FROM t1; a ROW(11, 12) = (SELECT a, 22) ROW(11, 12) IN (SELECT a, 22) 1 0 0 2 0 0 11 0 0 SELECT a, ROW(11, 12) = (SELECT a, 12), ROW(11, 12) IN (SELECT a, 12) FROM t1; a ROW(11, 12) = (SELECT a, 12) ROW(11, 12) IN (SELECT a, 12) 1 0 0 2 0 0 11 1 1 SELECT a AS x, ROW(11, 12) = (SELECT MAX(x), 22), ROW(11, 12) IN (SELECT MAX(x), 22) FROM t1; x ROW(11, 12) = (SELECT MAX(x), 22) ROW(11, 12) IN (SELECT MAX(x), 22) 1 0 0 2 0 0 11 0 0 # 2nd and 3rd columns should be same EXPLAIN SELECT a AS x, ROW(11, 12) = (SELECT MAX(x), 12), ROW(11, 12) IN (SELECT MAX(x), 12) FROM t1; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 3 3 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used 2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used SELECT a AS x, ROW(11, 12) = (SELECT MAX(x), 12), ROW(11, 12) IN (SELECT MAX(x), 12) FROM t1; x ROW(11, 12) = (SELECT MAX(x), 12) ROW(11, 12) IN (SELECT MAX(x), 12) 1 0 0 2 0 0 11 1 1 DROP TABLE t1; # both columns should be same SELECT ROW(1,2) = (SELECT NULL, NULL), ROW(1,2) IN (SELECT NULL, NULL); ROW(1,2) = (SELECT NULL, NULL) ROW(1,2) IN (SELECT NULL, NULL) NULL NULL SELECT ROW(1,2) = (SELECT 1, NULL), ROW(1,2) IN (SELECT 1, NULL); ROW(1,2) = (SELECT 1, NULL) ROW(1,2) IN (SELECT 1, NULL) NULL NULL SELECT ROW(1,2) = (SELECT NULL, 2), ROW(1,2) IN (SELECT NULL, 2); ROW(1,2) = (SELECT NULL, 2) ROW(1,2) IN (SELECT NULL, 2) NULL NULL SELECT ROW(1,2) = (SELECT NULL, 1), ROW(1,2) IN (SELECT NULL, 1); ROW(1,2) = (SELECT NULL, 1) ROW(1,2) IN (SELECT NULL, 1) 0 0 SELECT ROW(1,2) = (SELECT 1, 1), ROW(1,2) IN (SELECT 1, 1); ROW(1,2) = (SELECT 1, 1) ROW(1,2) IN (SELECT 1, 1) 0 0 SELECT ROW(1,2) = (SELECT 1, 2), ROW(1,2) IN (SELECT 1, 2); ROW(1,2) = (SELECT 1, 2) ROW(1,2) IN (SELECT 1, 2) 1 1 CREATE TABLE t1 (a INT, b INT, c INT); INSERT INTO t1 VALUES (1,1,1), (1,1,1); EXPLAIN EXTENDED SELECT c FROM ( SELECT (SELECT COUNT(a) FROM (SELECT COUNT(b) FROM t1) AS x GROUP BY c ) FROM t1 GROUP BY b ) AS y; ERROR 42S22: Unknown column 'c' in 'field list' SHOW WARNINGS; Level Code Message Note 1276 Field or reference 'test.t1.a' of SELECT #3 was resolved in SELECT #2 Note 1981 Aggregate function 'count()' of SELECT #3 belongs to SELECT #2 Note 1276 Field or reference 'test.t1.c' of SELECT #3 was resolved in SELECT #2 Error 1054 Unknown column 'c' in 'field list' DROP TABLE t1; End of 5.0 tests # # BUG#36896: Server crash on SELECT FROM DUAL # create table t1 (a int); select 1 as res from dual where (1) in (select * from t1); res drop table t1; create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 ( a int(11) default null, b int(11) default null, key (a) ); insert into t1 select A.a+10*(B.a+10*C.a),A.a+10*(B.a+10*C.a) from t0 A, t0 B, t0 C; create table t2 (a int(11) default null); insert into t2 values (0),(1); create table t3 (a int(11) default null); insert into t3 values (0),(1); create table t4 (a int(11) default null); insert into t4 values (0),(1); create table t5 (a int(11) default null); insert into t5 values (0),(1),(0),(1); select * from t2, t3 where t2.a < 10 and t3.a+1 = 2 and t3.a in (select t1.b from t1 where t1.a+1=t1.a+1 and t1.a < (select t4.a+10 from t4, t5 limit 2)); ERROR 21000: Subquery returns more than 1 row drop table t0, t1, t2, t3, t4, t5; # # BUG#48177 - SELECTs with NOT IN subqueries containing NULL # values return too many records # CREATE TABLE t1 ( i1 int DEFAULT NULL, i2 int DEFAULT NULL ) ; INSERT INTO t1 VALUES (1, NULL); INSERT INTO t1 VALUES (2, 3); INSERT INTO t1 VALUES (4, NULL); INSERT INTO t1 VALUES (4, 0); INSERT INTO t1 VALUES (NULL, NULL); CREATE TABLE t2 ( i1 int DEFAULT NULL, i2 int DEFAULT NULL ) ; INSERT INTO t2 VALUES (4, NULL); INSERT INTO t2 VALUES (5, 0); Data in t1 SELECT i1, i2 FROM t1; i1 i2 1 NULL 2 3 4 NULL 4 0 NULL NULL Data in subquery (should be filtered out) SELECT i1, i2 FROM t2 ORDER BY i1; i1 i2 4 NULL 5 0 FLUSH STATUS; set @save_optimizer_switch2=@@optimizer_switch; set optimizer_switch='subquery_cache=off'; SELECT i1, i2 FROM t1 WHERE (i1, i2) NOT IN (SELECT i1, i2 FROM t2); i1 i2 1 NULL 2 3 # Check that the subquery only has to be evaluated once # for all-NULL values even though there are two (NULL,NULL) records # Baseline: SHOW STATUS LIKE '%Handler_read_rnd_next'; Variable_name Value Handler_read_rnd_next 18 INSERT INTO t1 VALUES (NULL, NULL); FLUSH STATUS; SELECT i1, i2 FROM t1 WHERE (i1, i2) NOT IN (SELECT i1, i2 FROM t2); i1 i2 1 NULL 2 3 # Handler_read_rnd_next should be one more than baseline # (read record from t1, but do not read from t2) SHOW STATUS LIKE '%Handler_read_rnd_next'; Variable_name Value Handler_read_rnd_next 19 set @@optimizer_switch=@save_optimizer_switch2; DROP TABLE t1,t2; End of 5.1 tests CREATE TABLE t1 ( a int(11) NOT NULL, b int(11) NOT NULL, c datetime default NULL, PRIMARY KEY (a), KEY idx_bc (b,c) ); INSERT INTO t1 VALUES (406989,67,'2006-02-23 17:08:46'), (150078,67,'2005-10-26 11:17:45'), (406993,67,'2006-02-27 11:20:57'), (245655,67,'2005-12-08 15:59:08'), (406994,67,'2006-02-27 11:26:46'), (256,67,NULL), (398341,67,'2006-02-20 04:48:44'), (254,67,NULL),(1120,67,NULL), (406988,67,'2006-02-23 17:07:22'), (255,67,NULL), (398340,67,'2006-02-20 04:38:53'),(406631,67,'2006-02-23 10:49:42'), (245653,67,'2005-12-08 15:59:07'),(406992,67,'2006-02-24 16:47:18'), (245654,67,'2005-12-08 15:59:08'),(406995,67,'2006-02-28 11:55:00'), (127261,67,'2005-10-13 12:17:58'),(406991,67,'2006-02-24 16:42:32'), (245652,67,'2005-12-08 15:58:27'),(398545,67,'2006-02-20 04:53:13'), (154504,67,'2005-10-28 11:53:01'),(9199,67,NULL),(1,67,'2006-02-23 15:01:35'), (223456,67,NULL),(4101,67,NULL),(1133,67,NULL), (406990,67,'2006-02-23 18:01:45'),(148815,67,'2005-10-25 15:34:17'), (148812,67,'2005-10-25 15:30:01'),(245651,67,'2005-12-08 15:58:27'), (154503,67,'2005-10-28 11:52:38'); create table t11 select * from t1 where b = 67 AND (c IS NULL OR c > NOW()) order by 3 asc; create table t12 select * from t1 where b = 67 AND (c IS NULL OR c > NOW()) order by 3 desc; create table t21 select * from t1 where b = 67 AND (c IS NULL OR c > '2005-12-08') order by 3 asc; create table t22 select * from t1 where b = 67 AND (c IS NULL OR c > '2005-12-08') order by 3 desc; set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch='materialization=off'; update t22 set c = '2005-12-08 15:58:27' where a = 255; explain select t21.* from t21,t22 where t21.a = t22.a and t22.a in (select t12.a from t11, t12 where t11.a in(255,256) and t11.a = t12.a and t11.c is null) and t22.c is null order by t21.a; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t11 ALL NULL NULL NULL NULL 8 Using where; Start temporary; Using temporary; Using filesort 1 PRIMARY t12 hash_ALL NULL #hash#$hj 4 test.t11.a 8 Using where; Using join buffer (flat, BNLH join) 1 PRIMARY t22 hash_ALL NULL #hash#$hj 4 test.t11.a 26 Using where; End temporary; Using join buffer (incremental, BNLH join) 1 PRIMARY t21 hash_ALL NULL #hash#$hj 4 test.t11.a 26 Using where; Using join buffer (incremental, BNLH join) select t21.* from t21,t22 where t21.a = t22.a and t22.a in (select t12.a from t11, t12 where t11.a in(255,256) and t11.a = t12.a and t11.c is null) and t22.c is null order by t21.a; a b c 256 67 NULL set @@optimizer_switch=@save_optimizer_switch; drop table t1, t11, t12, t21, t22; create table t1(a int); insert into t1 values (0),(1); set @@optimizer_switch='firstmatch=off,materialization=off'; explain select (select max(Y.a) from t1 Y where a in (select a from t1 Z) and a < X.a) as subq from t1 X; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY X ALL NULL NULL NULL NULL 2 2 DEPENDENT SUBQUERY Y ALL NULL NULL NULL NULL 2 Using where 2 DEPENDENT SUBQUERY Z hash_ALL NULL #hash#$hj 5 test.Y.a 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) select (select max(Y.a) from t1 Y where a in (select a from t1 Z) and a < X.a) as subq from t1 X; subq NULL 0 set @@optimizer_switch=@save_optimizer_switch; drop table t1; create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 as select * from t0; insert into t1 select a+10 from t0; set @@optimizer_switch='firstmatch=off,materialization=off'; insert into t0 values(2); explain select * from t1 where 2 in (select a from t0); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 ALL NULL NULL NULL NULL 11 Using where; Start temporary; End temporary 1 PRIMARY t1 ALL NULL NULL NULL NULL 20 Using join buffer (flat, BNL join) select * from t1 where 2 in (select a from t0); a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch='materialization=off'; explain select * from t1 where 2 in (select a from t0); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 ALL NULL NULL NULL NULL 11 Using where; FirstMatch 1 PRIMARY t1 ALL NULL NULL NULL NULL 20 Using join buffer (flat, BNL join) select * from t1 where 2 in (select a from t0); a 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch='materialization=off'; set @tmp_optimizer_switch=@@optimizer_switch; set optimizer_switch='derived_merge=off,derived_with_keys=off'; explain select * from (select a from t0) X where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY ALL NULL NULL NULL NULL 11 1 PRIMARY t1 ALL NULL NULL NULL NULL 20 Using where; FirstMatch(); Using join buffer (flat, BNL join) 2 DERIVED t0 ALL NULL NULL NULL NULL 11 drop table t0, t1; set optimizer_switch=@tmp_optimizer_switch; create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (kp1 int, kp2 int, c int, filler char(100), key(kp1, kp2)); insert into t1 select A.a+10*(B.a+10*C.a), 0, 0, 'filler' from t0 A, t0 B, t0 C; insert into t1 select * from t1 where kp1 < 20; create table t3 (a int); insert into t3 select A.a + 10*B.a from t0 A, t0 B; explain select * from t3 where a in (select kp1 from t1 where kp1<20); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 range kp1 kp1 5 NULL 48 Using where; Using index; LooseScan 1 PRIMARY t3 ALL NULL NULL NULL NULL 100 Using where; Using join buffer (flat, BNL join) create table t4 (pk int primary key); insert into t4 select a from t3; explain select * from t3 where a in (select t1.kp1 from t1,t4 where kp1<20 and t4.pk=t1.c); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 100 Using where 1 PRIMARY t1 ref kp1 kp1 5 test.t3.a 1 Using where 1 PRIMARY t4 eq_ref PRIMARY PRIMARY 4 test.t1.c 1 Using index; FirstMatch(t3) drop table t1, t3, t4; set @@optimizer_switch=@save_optimizer_switch; create table t1 (a int) as select * from t0 where a < 5; set @save_max_heap_table_size=@@max_heap_table_size; set @@optimizer_switch='firstmatch=off,materialization=off'; set @@max_heap_table_size= 16384; explain select count(*) from t0 A, t0 B, t0 C, t0 D where D.a in (select a from t1 E where a+1 < 10000 + A.a + B.a +C.a+D.a); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY A ALL NULL NULL NULL NULL 10 1 PRIMARY B ALL NULL NULL NULL NULL 10 Using join buffer (flat, BNL join) 1 PRIMARY E ALL NULL NULL NULL NULL 5 Using where; Start temporary; Using join buffer (incremental, BNL join) 1 PRIMARY D hash_ALL NULL #hash#$hj 5 test.E.a 10 Using where; Using join buffer (incremental, BNLH join) 1 PRIMARY C ALL NULL NULL NULL NULL 10 Using where; End temporary; Using join buffer (incremental, BNL join) flush status; select count(*) from t0 A, t0 B, t0 C, t0 D where D.a in (select a from t1 E where a+1 < 10000 + A.a + B.a +C.a+D.a); count(*) 5000 show status like 'Created_tmp_disk_tables'; Variable_name Value Created_tmp_disk_tables 1 set @save_max_heap_table_size=@@max_heap_table_size; set @@optimizer_switch=@save_optimizer_switch; drop table t0, t1; create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t2(a int); insert into t2 values (1),(2); create table t3 ( a int , filler char(100), key(a)); insert into t3 select A.a + 10*B.a, 'filler' from t0 A, t0 B; explain select * from t3 where a in (select a from t2) and (a > 5 or a < 10); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY ALL distinct_key NULL NULL NULL 2 1 PRIMARY t3 ref a a 5 test.t2.a 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 2 MATERIALIZED t2 ALL NULL NULL NULL NULL 2 Using where select * from t3 where a in (select a from t2); a filler 1 filler 2 filler drop table t0, t2, t3; set @@optimizer_switch='firstmatch=off,materialization=off'; create table t1 (a date); insert into t1 values ('2008-01-01'),('2008-01-01'),('2008-02-01'),('2008-02-01'); create table t2 (a int); insert into t2 values (1),(2); create table t3 (a char(10)); insert into t3 select * from t1; insert into t3 values (1),(2); explain select * from t2 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where 1 PRIMARY t1 hash_ALL NULL #hash#$hj 4 test.t2.a 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) explain select * from t2 where a in (select a from t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where 1 PRIMARY t2 hash_ALL NULL #hash#$hj 5 test.t2.a 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) explain select * from t2 where a in (select a from t3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 1 PRIMARY t3 ALL NULL NULL NULL NULL 6 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) explain select * from t1 where a in (select a from t3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 1 PRIMARY t3 ALL NULL NULL NULL NULL 6 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) drop table t1, t2, t3; create table t1 (a decimal); insert into t1 values (1),(2); explain select * from t1 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where 1 PRIMARY t1 hash_ALL NULL #hash#$hj 6 test.t1.a 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) drop table t1; set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch='materialization=off'; create table t1 (a int); insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t2 as select * from t1; create table t3 (a int, b int, filler char(100), key(a)); insert into t3 select A.a + 10*B.a, A.a + 10*B.a, 'filler' from t1 A, t1 B, t1 C; explain select * from t1, t3 where t3.a in (select a from t2) and (t3.a < 10 or t3.a >30) and t1.a =3; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where 1 PRIMARY t2 ALL NULL NULL NULL NULL 10 Using where; Start temporary; Using join buffer (flat, BNL join) 1 PRIMARY t3 ref a a 5 test.t2.a 10 End temporary; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan explain select straight_join * from t1 A, t1 B where A.a in (select a from t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY A ALL NULL NULL NULL NULL 10 Using where 1 PRIMARY B ALL NULL NULL NULL NULL 10 Using join buffer (flat, BNL join) 2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 10 Using where explain select * from t2 where a in (select straight_join A.a from t1 A, t1 B); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 10 Using where 2 DEPENDENT SUBQUERY A ALL NULL NULL NULL NULL 10 Using where 2 DEPENDENT SUBQUERY B ALL NULL NULL NULL NULL 10 Using join buffer (flat, BNL join) explain select * from t2 where a in (select straight_join A.a from t1 A, t1 B); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 10 Using where 2 DEPENDENT SUBQUERY A ALL NULL NULL NULL NULL 10 Using where 2 DEPENDENT SUBQUERY B ALL NULL NULL NULL NULL 10 Using join buffer (flat, BNL join) explain select straight_join * from t2 X, t2 Y where X.a in (select straight_join A.a from t1 A, t1 B); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY X ALL NULL NULL NULL NULL 10 Using where 1 PRIMARY Y ALL NULL NULL NULL NULL 10 Using join buffer (flat, BNL join) 2 DEPENDENT SUBQUERY A ALL NULL NULL NULL NULL 10 Using where 2 DEPENDENT SUBQUERY B ALL NULL NULL NULL NULL 10 Using join buffer (flat, BNL join) create table t0 (a int, b int); insert into t0 values(1,1); explain select * from t0, t3 where t3.a in (select a from t2) and (t3.a < 10 or t3.a >30); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 system NULL NULL NULL NULL 1 1 PRIMARY t2 ALL NULL NULL NULL NULL 10 Using where; Start temporary 1 PRIMARY t3 ref a a 5 test.t2.a 10 End temporary; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan create table t4 as select a as x, a as y from t1; explain select * from t0, t3 where (t3.a, t3.b) in (select x,y from t4) and (t3.a < 10 or t3.a >30); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 system NULL NULL NULL NULL 1 1 PRIMARY t4 ALL NULL NULL NULL NULL 10 Using where; Start temporary 1 PRIMARY t3 ref a a 5 test.t4.x 10 Using where; End temporary; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan drop table t0,t1,t2,t3,t4; create table t0 (a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (a int, b int, filler char(100), key(a,b)); insert into t1 select A.a, B.a, 'filler' from t0 A, t0 B; create table t2 as select * from t1; explain select * from t2 where a in (select b from t1 where a=3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ref a a 5 const 8 Using index; LooseScan 1 PRIMARY t2 ALL NULL NULL NULL NULL 100 Using where; Using join buffer (flat, BNL join) explain select * from t2 where (b,a) in (select a,b from t1 where a=3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ref a a 5 const 8 Using index; LooseScan 1 PRIMARY t2 ALL NULL NULL NULL NULL 100 Using where; Using join buffer (flat, BNL join) drop table t1,t2; set @@optimizer_switch=@save_optimizer_switch; create table t1 (a int, b int); insert into t1 select a,a from t0; create table t2 (a int, b int); insert into t2 select A.a + 10*B.a, A.a + 10*B.a from t0 A, t0 B; set @@optimizer_switch='firstmatch=off,materialization=off'; explain select * from t1 where (a,b) in (select a,b from t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where 1 PRIMARY t2 hash_ALL NULL #hash#$hj 10 test.t1.a,test.t1.b 100 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) set @save_optimizer_search_depth=@@optimizer_search_depth; set @@optimizer_search_depth=63; Warnings: Warning 1292 Truncated incorrect optimizer_search_depth value: '63' explain select * from t1 where (a,b) in (select a,b from t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where 1 PRIMARY t2 hash_ALL NULL #hash#$hj 10 test.t1.a,test.t1.b 100 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) set @@optimizer_search_depth=@save_optimizer_search_depth; set @@optimizer_switch=@save_optimizer_switch; drop table t0, t1, t2; set @@optimizer_switch='materialization=off'; create table t0 (a decimal(4,2)); insert into t0 values (10.24), (22.11); create table t1 as select * from t0; insert into t1 select * from t0; explain select * from t0 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 ALL NULL NULL NULL NULL 2 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join) select * from t0 where a in (select a from t1); a 10.24 22.11 drop table t0, t1; create table t0(a date); insert into t0 values ('2008-01-01'),('2008-02-02'); create table t1 as select * from t0; insert into t1 select * from t0; explain select * from t0 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 ALL NULL NULL NULL NULL 2 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join) select * from t0 where a in (select a from t1); a 2008-01-01 2008-02-02 drop table t0, t1; create table t0(a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 as select a as a, a as b, a as c from t0 where a < 3; create table t2 as select a as a, a as b from t0 where a < 3; insert into t2 select * from t2; explain select * from t1 where (a,b,c) in (select X.a, Y.a, Z.a from t2 X, t2 Y, t2 Z where X.b=33); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 3 1 PRIMARY X ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join) 1 PRIMARY Y ALL NULL NULL NULL NULL 6 Using where; Using join buffer (incremental, BNL join) 1 PRIMARY Z ALL NULL NULL NULL NULL 6 Using where; FirstMatch(t1); Using join buffer (incremental, BNL join) drop table t0,t1,t2; set @@optimizer_switch=@save_optimizer_switch; BUG#37842: Assertion in DsMrr_impl::dsmrr_init, at handler.cc:4307 CREATE TABLE t1 ( `pk` int(11) NOT NULL AUTO_INCREMENT, `int_key` int(11) DEFAULT NULL, PRIMARY KEY (`pk`), KEY `int_key` (`int_key`) ) ENGINE=MyISAM; INSERT INTO t1 VALUES (1,9),(2,3),(3,8),(4,6),(5,9),(6,5),(7,5),(8,9),(9,1),(10,10); SELECT `pk` FROM t1 AS OUTR WHERE `int_key` = ALL ( SELECT `int_key` FROM t1 AS INNR WHERE INNR . `pk` >= 9 ); pk DROP TABLE t1; BUG#40118 Crash when running Batched Key Access and requiring one match for each key create table t0(a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (a int, key(a)); insert into t1 select * from t0; alter table t1 add b int not null, add filler char(200); insert into t1 select * from t1; insert into t1 select * from t1; set @save_join_cache_level=@@join_cache_level; set join_cache_level=6; select * from t0 where t0.a in (select t1.a from t1 where t1.b=0); a 0 1 2 3 4 5 6 7 8 9 set join_cache_level=@save_join_cache_level; drop table t0, t1; # # BUG#32665 Query with dependent subquery is too slow # create table t1 ( idIndividual int primary key ); insert into t1 values (1),(2); create table t2 ( idContact int primary key, contactType int, idObj int ); insert into t2 values (1,1,1),(2,2,2),(3,3,3); create table t3 ( idAddress int primary key, idContact int, postalStripped varchar(100) ); insert into t3 values (1,1, 'foo'), (2,2,'bar'); The following must be converted to a semi-join: set @save_optimizer_switch=@@optimizer_switch; set @@optimizer_switch='materialization=off'; explain extended SELECT a.idIndividual FROM t1 a WHERE a.idIndividual IN ( SELECT c.idObj FROM t3 cona INNER JOIN t2 c ON c.idContact=cona.idContact WHERE cona.postalStripped='T2H3B2' ); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY cona ALL NULL NULL NULL NULL 2 100.00 Using where; Start temporary 1 PRIMARY c eq_ref PRIMARY PRIMARY 4 test.cona.idContact 1 100.00 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 PRIMARY a eq_ref PRIMARY PRIMARY 4 test.c.idObj 1 100.00 Using index; End temporary Warnings: Note 1003 select `test`.`a`.`idIndividual` AS `idIndividual` from `test`.`t1` `a` semi join (`test`.`t3` `cona` join `test`.`t2` `c`) where `test`.`cona`.`postalStripped` = 'T2H3B2' and `test`.`a`.`idIndividual` = `test`.`c`.`idObj` and `test`.`c`.`idContact` = `test`.`cona`.`idContact` set @@optimizer_switch=@save_optimizer_switch; drop table t1,t2,t3; # # BUG#47367 Crash in Name_resolution_context::process_error # SET SESSION optimizer_switch = 'semijoin=off'; CREATE TABLE t1 (f1 INTEGER); CREATE TABLE t2 LIKE t1; CREATE PROCEDURE p1 () BEGIN SELECT f1 FROM t1 WHERE f1 IN (SELECT f1 FROM t2); END| CALL p1; f1 ALTER TABLE t2 CHANGE COLUMN f1 my_column INT; CALL p1; f1 DROP PROCEDURE p1; # Restore the original column list of table t2: ALTER TABLE t2 CHANGE COLUMN my_column f1 INT; SET SESSION optimizer_switch = 'semijoin=on'; # Recreate procedure so that we eliminate any caching effects CREATE PROCEDURE p1 () BEGIN SELECT f1 FROM t1 WHERE f1 IN (SELECT f1 FROM t2); END| CALL p1; f1 ALTER TABLE t2 CHANGE COLUMN f1 my_column INT; CALL p1; ERROR 42S22: Unknown column 'f1' in 'where clause' DROP PROCEDURE p1; DROP TABLE t1, t2; # # fix of lp:824425 (prohibiting subqueries in row in # left part of IN/ALL/ANY) # CREATE TABLE t1 ( a int) ; INSERT INTO t1 VALUES (20),(30); CREATE TABLE t2 (a int) ; INSERT INTO t2 VALUES (3),(9); CREATE TABLE t3 ( a int, b int) ; INSERT INTO t3 VALUES (20,5),(30,6); set @optimizer_switch_save=@@optimizer_switch; SET SESSION optimizer_switch='semijoin=OFF,in_to_exists=OFF,materialization=ON,partial_match_rowid_merge=ON,partial_match_table_scan=OFF'; SELECT * FROM t1 WHERE ( ( SELECT a FROM t2 WHERE a = 9 ) ) NOT IN ( SELECT b FROM t3 ); a 20 30 explain extended SELECT * FROM t1 WHERE ( ( SELECT a FROM t2 WHERE a = 9 ) ) NOT IN ( SELECT b FROM t3 ); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 100.00 3 MATERIALIZED t3 ALL NULL NULL NULL NULL 2 100.00 2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 100.00 Using where Warnings: Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where 1 SELECT * FROM t1 WHERE ( ( SELECT a FROM t2 WHERE a = 9 ), ( SELECT a FROM t2 WHERE a = 3 ) ) NOT IN ( SELECT b , a FROM t3 ); ERROR 42000: This version of MariaDB doesn't yet support 'SUBQUERY in ROW in left expression of IN/ALL/ANY' set optimizer_switch=@optimizer_switch_save; drop table t1,t2,t3; End of 5.3 tests # # BUG#48920: COUNT DISTINCT returns 1 for NULL values when in a subquery # in the select list # CREATE TABLE t1 ( i int(11) DEFAULT NULL, v varchar(1) DEFAULT NULL ); INSERT INTO t1 VALUES (8,'v'); INSERT INTO t1 VALUES (9,'r'); INSERT INTO t1 VALUES (NULL,'y'); CREATE TABLE t2 ( i int(11) DEFAULT NULL, v varchar(1) DEFAULT NULL, KEY i_key (i) ); INSERT INTO t2 VALUES (NULL,'r'); INSERT INTO t2 VALUES (0,'c'); INSERT INTO t2 VALUES (0,'o'); INSERT INTO t2 VALUES (2,'v'); INSERT INTO t2 VALUES (7,'c'); SELECT i, v, (SELECT COUNT(DISTINCT i) FROM t1 WHERE v = t2.v) as subsel FROM t2; i v subsel NULL r 1 0 c 0 0 o 0 2 v 1 7 c 0 EXPLAIN EXTENDED SELECT i, v, (SELECT COUNT(DISTINCT i) FROM t1 WHERE v = t2.v) as subsel FROM t2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 5 100.00 2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 3 100.00 Using where Warnings: Note 1276 Field or reference 'test.t2.v' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`i` AS `i`,`test`.`t2`.`v` AS `v`,<`test`.`t2`.`v`>((/* select#2 */ select count(distinct `test`.`t1`.`i`) from `test`.`t1` where `test`.`t1`.`v` = `test`.`t2`.`v`)) AS `subsel` from `test`.`t2` DROP TABLE t1,t2; End of 5.6 tests set @@optimizer_switch=@subselect3_tmp; set join_cache_level=default; show variables like 'join_cache_level'; Variable_name Value join_cache_level 2 set @@optimizer_switch=@save_optimizer_switch; set @join_cache_level_for_subselect3_test=NULL;