Updates to tsdemo2 records that don't actually modify a column cause no change to TIMESTAMP values
mysql> mysql> mysql> CREATE TABLE tsdemo2 -> ( -> t_update TIMESTAMP, # record last-modification time -> t_create TIMESTAMP, # record creation time -> val INT -> ); Query OK, 0 rows affected (0.00 sec) mysql> mysql> INSERT INTO tsdemo2 (t_update,t_create,val) VALUES(NULL,NULL,5); Query OK, 1 row affected (0.00 sec) mysql> SELECT * FROM tsdemo2; +---------------------+---------------------+------+ | t_update | t_create | val | +---------------------+---------------------+------+ | 2011-10-03 13:05:52 | 2011-10-03 13:05:52 | 5 | +---------------------+---------------------+------+ 1 row in set (0.00 sec) mysql> mysql> UPDATE tsdemo2 SET val = val + 1; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> SELECT * FROM tsdemo2; +---------------------+---------------------+------+ | t_update | t_create | val | +---------------------+---------------------+------+ | 2011-10-03 13:05:52 | 2011-10-03 13:05:52 | 6 | +---------------------+---------------------+------+ 1 row in set (0.00 sec) mysql> mysql> UPDATE tsdemo2 SET val = val + 0; Query OK, 0 rows affected (0.00 sec) Rows matched: 1 Changed: 0 Warnings: 0 mysql> SELECT * FROM tsdemo2; +---------------------+---------------------+------+ | t_update | t_create | val | +---------------------+---------------------+------+ | 2011-10-03 13:05:52 | 2011-10-03 13:05:52 | 6 | +---------------------+---------------------+------+ 1 row in set (0.00 sec) mysql> mysql> mysql> drop table tsdemo2; Query OK, 0 rows affected (0.00 sec)