Some interval specifiers comprise both date and time parts.
mysql>
mysql> SELECT NOW( ), DATE_ADD(NOW( ),INTERVAL '14:30' HOUR_MINUTE);
+---------------------+-----------------------------------------------+
| NOW( ) | DATE_ADD(NOW( ),INTERVAL '14:30' HOUR_MINUTE) |
+---------------------+-----------------------------------------------+
| 2011-10-03 13:05:47 | 2011-10-04 03:35:47 |
+---------------------+-----------------------------------------------+
1 row in set (0.00 sec)
mysql>
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