1. select * from ta as a inner join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm 2. select * from ta as a left join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm where b.cid is null and b.name is null and b.wpdm is null
1. select * from ta as a inner join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm 2. select * from ta as a left join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm 就直接一个inner join 和 left join就可以了
select * from ta as a inner join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm
2.
select * from ta as a left join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm
where b.cid is null and b.name is null and b.wpdm is null
select * from ta as a inner join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm
2.
select * from ta as a left join tb as b on a.cid = b.cid and a.name = b.name and a.wpdm = b.wpdm
就直接一个inner join 和 left join就可以了