三表连接a,b,c a和b先内连接,再和c外连接,db2 该怎么写select * from a inner join bon a.id = b.idleft outer join c on b.oid = c.oid这样写对不对?
select * from (select * from a inner join b on a.id=b.id) t out join c on t.id=c.id