TIMESTAMP(expr1,expr2) adds the time expression expr2 to the date or datetime expression expr1 and returns the result as a datetime value. : TIMESTAMP « Date Time Functions « MySQL Tutorial

1. MySQL Tutorial
2. Date Time Functions
3. TIMESTAMP

mysql>
mysql>
mysql> SELECT TIMESTAMP('2003-12-31 12:00:00','12:00:00');
+---------------------------------------------+
| TIMESTAMP('2003-12-31 12:00:00','12:00:00') |
+---------------------------------------------+
| 2004-01-01 00:00:00                         |
+---------------------------------------------+
1 row in set (0.00 sec)

mysql>