mariadb/mysql-test/t/subselect.test

select (select 2);
drop table if exists t1,t2,t3,t4;
create table t1 (a int);
create table t2 (a int, b int);
create table t3 (a int);
create table t4 (a int, b int);
insert into t1 values (2);
insert into t2 values (1,7),(2,7);
insert into t4 values (4,8),(3,8),(5,9);
select (select a from t1 where t1.a=t2.a), a from t2;
select (select a from t1 where t1.a=t2.b), a from t2;
select (select a from t1), a from t2;
select (select a from t3), a from t2;
select * from t2 where t2.a=(select a from t1);
insert into t3 values (6),(7),(3);
select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1);
select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1) 
union (select * from t4 order by a limit 2) limit 3;
select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1) 
union (select * from t4 where t4.b=(select max(t2.a)*4 from t2) order by a);
select (select a from t3 where a<t2.a*4 order by 1 desc limit 1), a from t2;
select (select t3.a from t3 where a<8 order by 1 desc limit 1), a from 
(select * from t2 where a>1) as tt;
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3) order by 1 desc limit 1);
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3 where t3.a > t1.a) order by 1 desc limit 1);
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3 where t3.a < t1.a) order by 1 desc limit 1);
select b,(select avg(t2.a+(select min(t3.a) from t3 where t3.a >= t4.a)) from t2) from t4;
drop table t1,t2,t3,t4;