每个城市是指供应商所在城市 还是 零件存放的城市?
try->
select P.city,P.PName,S.SName,max(a.sumqty) from
(
(select SNO,PNO,SUM(QTY) as sumqty from SPJ group by SNO,PNO) a
join S on a.sno=S.SNO
join P on a.PNO=p.PNO
) t
group by P.city,P.PName,S.SName
try->
select P.city,P.PName,S.SName,max(a.sumqty) from
(
(select SNO,PNO,SUM(QTY) as sumqty from SPJ group by SNO,PNO) a
join S on a.sno=S.SNO
join P on a.PNO=p.PNO
) t
group by P.city,P.PName,S.SName
select P.city,P.PName,S.SName,max(a.sumqty) from
(
(select SNO,PNO,SUM(QTY) as sumqty from SPJ group by SNO,PNO) a
join S on a.sno=S.SNO
join P on a.PNO=p.PNO
) t
group by P.city,P.PName,S.SName
select S.SName,a.sumqty from S left join
(
(select s.SNO,p.PNO,SUM(QTY) as sumqty from SPJ group by SNO,PNO) a
left join S on a.sno=S.SNO
left join P on a.PNO=p.PNO
) t
on s.sno = a.sno
select S.SName,a.sumqty from S left join
(
(select s.SNO,p.PNO,SUM(QTY) as sumqty from SPJ group by SNO,PNO) a
left join S on a.sno=S.SNO
left join P on a.PNO=p.PNO
) t
on s.sno = t.sno