Introduction MySQL Tutorial

MySQL Server parses and executes the code within the comment.
Other SQL servers will ignore the extensions.
If you add a version number after the ! character, the syntax within the comment is executed only if the MySQL version is greater than or equal to the specified version number.

mysql>
mysql> CREATE /*!32302 TEMPORARY */ TABLE t (a INT);
Query OK, 0 rows affected (0.02 sec)
mysql>
mysql> desc t;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| a     | int(11) | YES  |     | NULL    |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)
mysql>
mysql> drop table t;
Query OK, 0 rows affected (0.00 sec)
mysql>