Mega Code Archive
Transform the time differences into seconds using TIME_TO_SEC, add them, and then convert them back
<![CDATA[
mysql>
mysql> CREATE TABLE mytable (
-> id INT AUTO_INCREMENT,
-> begintime DATETIME,
-> endtime DATETIME,
-> PRIMARY KEY (id)
-> );
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql> INSERT INTO mytable (begintime, endtime) VALUES
-> ('2005-03-27 7:15', '2005-03-27 18:00'),
-> ('2005-03-28 8:00', '2005-03-28 18:00'),
-> ('2005-03-29 7:30', '2005-03-29 16:50'),
-> ('2005-03-30 7:00', '2005-03-30 17:15');
Query OK, 4 rows affected (0.00 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(TIMEDIFF(endtime, begintime)))) AS sumtime FROM mytable;
+----------+
| sumtime |
+----------+
| 40:20:00 |
+----------+
1 row in set (0.00 sec)
mysql>
mysql> drop table mytable;
Query OK, 0 rows affected (0.00 sec)
mysql>
]]>