create table chat_content
(
   chat_content_id                int(11)                        not null AUTO_INCREMENT,
   from_id                        int(11)                        not null,
   to_id                          int(11)                        not null,
   content                        text                           default NULL,
   chat_time                      datetime,
   primary key (chat_content_id),
}

/*==============================================================*/
/* TRIGGER: chat_content_trig       chat_content   insert用     */
/*==============================================================*/
CREATE TRIGGER chat_content_trig after insert
ON chat_content FOR EACH ROW 

BEGIN
    update chat_content set chat_time =(select sysdate()) 
        where chat_content_id=new.chat_content_id
END;