sql-server - 将表 B 中的列的值设置为表 A 中的列的最大值

Question

我有两个这样的表：

Application  
ApplicationID  ApplicationDesc  VersionNo
1              APP1             1
2              APP2             1
3              APP3             1
4              APP1             2 
5              APP2             2
6              APP1             3

Order
OrderID      ApplicationID      OrderDescription
1            1                  Belongs to APP1 version 1
2            4                  Belongs to APP1 version 2
3            6                  Belongs to APP1 version 3

我想用相应应用程序的最新版本的 ApplicationID 更新表 Order 中的 ApplicationID 列。

我希望数据看起来像这样：

Order
OrderID      ApplicationID      OrderDescription
1            6                  Belongs to APP1 version 1
2            6                  Belongs to APP1 version 2
3            6                  Belongs to APP1 version 3

我该如何做到这一点？请帮忙。

Answer 1

您可以使用公用表表达式来查找最新的 ApplicationID，然后将您的更新语句加入 CTE：

;WITH cteNewest(ApplicationID, NewestApplicationID)
AS(
  SELECT
     ApplicationID
    ,MAX(ApplicationID) OVER(PARTITION BY ApplicationDesc)
  FROM Application
)

UPDATE o
SET o.ApplicationID = new.NewestApplicationID
FROM [Order] o
JOIN cteNewest new
  ON o.ApplicationID = new.ApplicationID;

有一个SQLFiddle