1. MySQL



create_time` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
`update_time` datetime DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',


2. PG



"create_time" timestamp(6) DEFAULT ('now'::text)::timestamp(6) with time zone,
更新操作好像要用到触发器,待补充