select s.id, s.name, s.class_id, s.score, c.name classname from students s right outer join classes c on s.class_id=c.id union select s.id, s.name, s.class_id, s.score, c.name calssname from students s left outer join classes c on s.class_id=c.id;
Sign in to make a reply
_炫Z_楚昭