drop table if exists t1,t2,t3;
CREATE TABLE t1 (a int not null, b char (10) not null);
insert into t1 values(1,'a'),(2,'b'),(3,'c'),(3,'c');
CREATE TABLE t2 (a int not null, b char (10) not null);
insert into t2 values (3,'c'),(4,'d'),(5,'f'),(6,'e');
select t1.a,t3.y from t1,(select a as y from t2  where b='c') as t3  where t1.a = t3.y;
a	y
3	3
3	3
select t1.a,t3.a from t1,(select * from t2  where b='c') as t3  where t1.a = t3.a;
a	a
3	3
3	3
CREATE TABLE t3 (a int not null, b char (10) not null);
insert into t3 values (3,'f'),(4,'y'),(5,'z'),(6,'c');
select t1.a,t4.y from t1,(select t2.a as y from t2,(select t3.b from t3 where t3.a>3) as t5  where t2.b=t5.b) as t4  where t1.a = t4.y;
a	y
3	3
3	3
SELECT a FROM (SELECT 1 FROM (SELECT 1) HAVING a=1);
Unknown column 'a' in 'having clause'
SELECT a,b as a FROM (SELECT '1' as a,'2' as b) HAVING a=1;
Column: 'a' in having clause is ambiguous
SELECT a,2 as a FROM (SELECT '1' as a) HAVING a=2;
a	a
1	2
SELECT a,2 as a FROM (SELECT '1' as a) HAVING a=1;
a	a
SELECT 1 FROM (SELECT 1) WHERE a=2;
Unknown column 'a' in 'where clause'
SELECT (SELECT 1) as a FROM (SELECT 1 FROM t1  HAVING a=1);
Unknown column 'a' in 'having clause'
drop table if exists  t1.t2,t3;
select * from (select 1);
1
1
select a from (select 1 as a);
a
1
select 1 from (select 1);
1
1