It’s found that Mysql can automatic initialize and update a TIMESTAMP field just using creating table declaration. MsSql can also finish this job through a trigger, but it’s boring.

CREATE TABLE t1 (
  f1 TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                ON UPDATE CURRENT_TIMESTAMP);

Reference:
http://dev.mysql.com/doc/refman/5.0/en/timestamp-initialization.html
http://stackoverflow.com/questions/36001/sql-server-2005-auto-updated-datetime-column-lastupdated