Question

这些是我的表格：

会员：Id, Points
购物车注册：Id, Member_Id, CartId, RegisterDate, Point
SelectetMembers ：Id, Member_Id

会员可以在CartRegister和Member.Points中注册购物车。必须计算和插入会员所获得的所有积分。所以我需要计算每个SelectedMembers的所有点并更新Member表，但我不知道如何实现它。

以下脚本在我脑海中：

UPDATE [Member]
   SET [Points]=
    (
       SELECT SUM([CR].[Point]) AS [AllPoints]
       FROM  [CartRegister] AS [CR] 
       WHERE [CR].[Member_Id] = --???

    )
    WHERE [Members].[Member].[Id] IN  ( SELECT Member_Id From SelectedMembers  )

所以如果我使用

，我对Select Sum(Point)中的where子句感到困惑

        WHERE [CR].[Member_Id] IN ( Select Member_Id From SelectedMembers  )

然后所有成员的总和与所有成员点数的总和相同，也许我需要foreach你的建议是什么？

Answer 1

您可以使用CTE（公用表表达式）首先计算每个成员的点数，然后使用该更改来更新Members表：

-- this CTE takes all selected members, and calculates their total of points
;WITH MemberPoints AS
(
   SELECT 
       Member_ID,
       AllPoints = SUM(Point)
   FROM  
       CartRegister
   WHERE
       Member_ID IN (SELECT ID FROM SelectedMembers)
   GROUP BY 
       Member_ID
)
UPDATE dbo.Member  
SET Points = mp.AllPoints
FROM MemberPoints mp
WHERE dbo.Member.Member_ID = mp.Member_ID

Answer 2

@marc_s's solution的变体基本相同，只使用略有不同的语法：

WITH aggregated AS (
  SELECT
    *,
    AllPoints = SUM(Point) OVER (PARTITION BY Member_ID)
  FROM CartRegister
  WHERE Member_ID IN (SELECT ID FROM SelectedMembers)
)
UPDATE aggregated
SET Points = AllPoints

Answer 3

检查一下：

UPDATE [Member]
SET [Points]=
(
   SELECT SUM([CR].[Point]) AS [AllPoints]
   FROM  [CartRegister] AS [CR] 
   WHERE [CR].[Member_Id] = [Member].[Id]

)
WHERE [Members].[Member].[Id] IN  ( SELECT Member_Id From SelectedMembers  )

计算SQL中所选Ids的列总和

3 个答案: