Question

我有下表：

SystemList

System  Value1  Value2  Value3  Value4  Total

System1   10               30     40
System2           20
System3   10               30
System4           30              40

我在触发器中有以下工作正常但我想迭代每个系统并更新每行的总计而不必实际执行92次。有插入或更新时，是否有办法查找系统并累计该行中的值？

Use Database

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
               FROM dbo.SystemList where System = 'System1') Where System = 'System1'  

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
           FROM dbo.SystemList where System = 'System2') Where System = 'System2'

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
           FROM dbo.SystemList where System = 'System3') Where System = 'System3' 

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
           FROM dbo.SystemList where System = 'System4') Where System = 'System4'

我的实际触发器是：

USE [Database]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER TRIGGER [dbo].[Total]
   ON  [dbo].[SystemList]
   AFTER  INSERT,UPDATE
AS 

Begin

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
               FROM dbo.SystemList where System = 'System1') Where System = 'System1'  

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
           FROM dbo.SystemList where System = 'System2') Where System = 'System2'

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
           FROM dbo.SystemList where System = 'System3') Where System = 'System3' 

UPDATE dbo.SystemList
SET Total = (SELECT (COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0)) AS Total
           FROM dbo.SystemList where System = 'System4') Where System = 'System4'   

End

Answer 1

您不必在单独的查询中指定每个值，就像您正在做的那样。这会更简单。

或者你可以更轻松地做到这一点。改为使用表格中的计算列，您甚至不需要触发器。

UPDATE dbo.SystemList SET Total = COALESCE(Value1, 0) + COALESCE(Value2, 0) + COALESCE(Value3, 0) + COALESCE(Value4, 0))

https://msdn.microsoft.com/en-us/library/ms188300.aspx

从select语句循环更新触发器

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