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 filtered Extra
1 PRIMARY t6 ALL NULL NULL NULL NULL 4 100.00 Using where
2 DEPENDENT SUBQUERY t7 eq_ref PRIMARY PRIMARY 4 t6.clinic_uq 1 100.00 Using where; Using index
2 DEPENDENT SUBQUERY t7 eq_ref PRIMARY PRIMARY 4 test.t6.clinic_uq 1 100.00 Using index
Warnings:
Note 1276 Field or reference 'test.t6.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 1 AS `Not_used` from `test`.`t7` where (`test`.`t7`.`uq` = `test`.`t6`.`clinic_uq`))
...
...
@@ -1741,7 +1741,7 @@ Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`text` AS `text` from `tes
explain extended select * from t1 as tt where not exists (select id from t1 where id < 8 and (id = tt.id or id is null) having id is not null);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY tt ALL NULL NULL NULL NULL 12 100.00 Using where
2 DEPENDENT SUBQUERY t1 eq_ref PRIMARY PRIMARY 4 tt.id 1 100.00 Using where; Using index
2 DEPENDENT SUBQUERY t1 eq_ref PRIMARY PRIMARY 4 test.tt.id 1 100.00 Using where; Using index
Warnings:
Note 1276 Field or reference 'test.tt.id' of SELECT #2 was resolved in SELECT #1
Note 1003 select `test`.`tt`.`id` AS `id`,`test`.`tt`.`text` AS `text` from `test`.`t1` `tt` where (not(exists(select `test`.`t1`.`id` AS `id` from `test`.`t1` where ((`test`.`t1`.`id` < 8) and (`test`.`t1`.`id` = `test`.`tt`.`id`)) having (`test`.`t1`.`id` is not null))))
