以前在 SQL Server/T-SQL 中基于多列运行总计

Question

我正在努力在 SQL Server 中添加一个具有运行总计的表，我希望能得到您的帮助。

我有一张这样开始的桌子：

EPDate             Item               BuyItem
----------------------------------------------
20150101           Mouse              10
20150101           Keyboard           100
20150202           Mouse              20
20150202           Keyboard           200

我要生成下表：

EPDate             Item        RunningTotal           Previous Running Total 
----------------------------------------------------------------------------
20150101           Mouse              10                        0
20150202           Mouse              30                        10
20150101           Keyboard           100                       0
20150202           Keyboard           300                       100

我需要有关 Previous Running Total 列的帮助，因为我实际上能够使用以下查询生成 RunningTotal 列：

SELECT 
    *,
    SUM() OVER(PARTITION BY Item, ORDER BY EPDate) AS RunningTotal
FROM
    MySampleTable
ORDER BY 
    Item DESC

但是，鉴于我在不同的日期有两个不同的类别（鼠标、键盘），我该如何创建“上一个运行总计”列？

提前谢谢你！

Answer 1

您如何从运行总计中减去该值并按如下方式修改您的原始查询。

SELECT 
    *,
    SUM(BuyItem) OVER(PARTITION BY Item, ORDER BY EPDate) AS RunningTotal,
    SUM(BuyItem) OVER(PARTITION BY Item, ORDER BY EPDate) - BuyItem AS Previous Running Total
FROM
    MySampleTable
ORDER BY 
    Item DESC

Answer 2

这样试试

 SELECT *, SUM() OVER(PARTITION BY Item, ORDER BY EPDate) AS RunningTotal 
         , SUM() OVER(PARTITION BY Item, ORDER BY EPDate) - BuyItem  AS PreviousRunningTotal 
 FROM MySampleTable 

Answer 3

你可以使用lag()函数

DEMO

SELECT *,SUM(buyItem) OVER(PARTITION BY Item ORDER BY EPDate) AS RunningTotal,
lag(BuyItem) over(PARTITION BY Item order by EPDate) as [Previous Running Total]
FROM MySampleTable order by item

输出：

d           item      buyItem     RunningTotal  Previous Running Total
20150101    Keyboard   100         100              0
20150202    Keyboard   200         300             100
20150101    Mouse       10         10              0
20150202    Mouse       20         30              10