用联合查询select * from ((select b.id,b.name from a,b where a.id=b.id) union (select c.id,c.name from a,c where a.id=c.id)) temtable
select b.id,b.name from a left outer join b on a.id=b.id union select c.id,c.name from a left outer join c on a.id=c.id union select b.id,c.name from a left outer join b on a.id=b.id left outer join c on a.name=c.name
select a.*,b.*,c.* from A a Left Join B b on a.id=b.id Left Join C c on a.id=c.id
union
select c.id,c.name from a left outer join c on a.id=c.id
union
select b.id,c.name from a left outer join b on a.id=b.id left outer join c on a.name=c.name
select a.*,b.*,c.* from A a
Left Join B b on a.id=b.id
Left Join C c on a.id=c.id