sql不同表相同的CID qty2替换qt1数量
select TestA.CID,
(case when QTY2 != QTY then QTY2 else QTY end ) as QTY
from TestA
left join TestB on TestA.CID = TestB.CID
思想万有引力
select TestA.CID,
(case when QTY2 != QTY then QTY2 else QTY end ) as QTY
from TestA
left join TestB on TestA.CID = TestB.CID