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SQL code:
mysql> create table tab_B(id int primary key auto_increment,username varchar(20
);
Query OK, 0 rows affected (0.09 sec)
mysql> insert into tab_A values('A');
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql> insert into tab_A(username) values('A');
Query OK, 1 row affected (0.05 sec)
mysql> insert into tab_A(username) values('B');
Query OK, 1 row affected (0.05 sec)
mysql> insert into tab_B(username) values('C');
Query OK, 1 row affected (0.05 sec)
mysql> insert into tab_B(username) values('D');
Query OK, 1 row affected (0.05 sec)
mysql> [color=#FF0000]select * from tab_a union all select * from tab_b;[/color]
+----+----------+
| id | username |
+----+----------+
| 1 | A |
| 2 | B |
| 1 | C |
| 2 | D |
+----+----------+
4 rows in set (0.00 sec)
mysql>
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