MySql 생성 및 갱신시에 자동 갱신 타이스탬프컬럼 만들기

http://www.kbedell.com/2009/03/07/how-to-create-a-timestampdatetime-column-in-mysql-to-automatically-be-set-with-the-current-time/


e.g.) 
ALTER TABLE sms_regular_msg_default MODIFY mod_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '수정일'