select * from empcource a full join empinfo b on a.cource_id=b.cource_id ;-- cannot use in mysql ，instead of follow statement: left join union right join


select * from empcource a left join empinfo b on a.cource_id=b.cource_id
union
select * from empcource a right join empinfo b on a.cource_id=b.cource_id ;