同一张表内、利用变化的上一行数据动态地修改下一行数据(示例Demo)

--同一张表内、利用变化的上一行数据动态地修改下一行数据(示例Demo)

select identity(int,1,1) as [id],* into # from account order by [month] asc

CREATE TABLE #Temp (

[id] [int] NOT NULL,

[Month] [datetime] NOT NULL ,

[PlanFare] [money] NULL ,

[PutoutFare] [money] NULL ,

[PlanPreFare] [money] NULL ,

[PutoutPreFare] [money] NULL

)

declare @id int

declare m cursor for select [id] from # order by [id] asc

open m

fetch next from m into @id

while (@@fetch_status=0)

begin

insert into #Temp([id],[Month], PlanFare, PutoutFare, PlanPreFare, PutoutPreFare)

select [id],[Month], PlanFare, PutoutFare, PlanPreFare, PutoutPreFare from # where [id]=@id

UPDATE #

SET #.PlanPreFare = (a.PlanFare - a.putoutFare) + (a.PlanPreFare - a.putoutPreFare)

FROM #Temp AS a

WHERE #.[id] = a.[id]+1

--前行作依据，后行来修改(此次的后行，变成下次的前行，依此循环，直至表中的行遍历结束)

truncate table #Temp

fetch next from m into @id

end

close m

deallocate m

UPDATE Account

SET Account.PlanPreFare = a.PlanPreFare

FROM # AS a

WHERE Account.[Month] = a.[Month]

drop table #

drop table #Temp