6
6
select * from (select 2) b;
7
8
SELECT 1 as a FROM (SELECT 1 UNION SELECT a) b;
8
10
SELECT 1 as a FROM (SELECT a UNION SELECT 1) b;
9
11
CREATE TABLE t1 (a int not null, b char (10) not null);
10
12
insert into t1 values(1,'a'),(2,'b'),(3,'c'),(3,'c');