mysql> explain select 1 in (select 1 union select 2);
+----+--------------------+------------+------+---------------+------+---------+------+------+----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+------------+------+---------------+------+---------+------+------+----------------+
| 1 | PRIMARY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
| 2 | DEPENDENT SUBQUERY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
| 3 | DEPENDENT UNION | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
| NULL | UNION RESULT | <union2,3> | ALL | NULL | NULL | NULL | NULL | NULL | |
+----+--------------------+------------+------+---------------+------+---------+------+------+----------------+
4 rows in set (0.00 sec)
mysql> notee
|