mysql>
mysql> select DATE_SUB(curdate(), INTERVAL 1.1 HOUR_MICROSECOND);
+----------------------------------------------------+
| DATE_SUB(curdate(), INTERVAL 1.1 HOUR_MICROSECOND) |
+----------------------------------------------------+
| 2007-07-21 23:59:58.999999 |
+----------------------------------------------------+
1 row in set (0.00 sec)
mysql>