在 ms-sql 中计算累积总和

Question

我有一个具有以下结构的表 tblsumDemo

billingid  qty  Percent_of_qty  cumulative 
   1        10      5              5
   2        5       8              13(5+8)
   3        12      6              19(13+6)
   4        1       10             29(19+10)
   5        2       11             40(11+10) 

这是我尝试过的

declare @s int
 SELECT billingid, qty, Percent_of_qty,
       @s = @s + Percent_of_qty AS cumulative
FROM tblsumDemo
CROSS JOIN (SELECT @s = 0) AS var
ORDER BY billingid

但我无法获得所需的输出，任何帮助将不胜感激，谢谢

Answer 1

您可以使用CROSS APPLY：

SELECT 
    t1.*,
    x.cumulative
FROM tblSumDemo t1
CROSS APPLY(
    SELECT 
        cumulative = SUM(t2.Percent_of_Qty)
    FROM tblSumDemo t2
    WHERE t2.billingid <= t1.billingid
)x

对于 SQL Server 2012+，您可以使用SUM OVER()：

SELECT *,
    cummulative = SUM(Percent_of_Qty) OVER(ORDER BY billingId)
FROM tblSumDemo