-- 第一句:
select * from tableA where pid in(select pid from tableB where piid in(select piid from tableC where oiid=number));
-- 第二句:
select A.* from tableA,tableB,tableC where C.oiid=number and c.piid=B.piid and B.pid=A.pid;
条件:number是查询的输入id
-- T1:oiid=number;
-- T2:B.piid=C.piid
-- T3:A.pid=B.pid