select a.id1,a.id2,b.name as name1,c.name as name2from 表A a left join 表B b on a.id1=b.idleft join 表B c on a.id2=c.id
select A.id1,a.id2,c.name name1,d.name name2 from A, B c, B dwhere c.id=a.id1 and d.id=a.id2