select * from bond as A
where changedate =
(select max(changedate) from bond where DealMarket = A.DealMarket and DealCode = A.DealCode and ChangeDate <= @ChangeDate)
where changedate =
(select max(changedate) from bond where DealMarket = A.DealMarket and DealCode = A.DealCode and ChangeDate <= @ChangeDate)
请问DealMarket = A.DealMarket and DealCode = A.DealCode 的作用是什麽???谢谢!
and and ChangeDate <= '2003-05-20')
dealcode=tem.dealcode
的作用是限定自查询里的dealcode等于外面的dealcode,在这个结果范围内求最大的