sql - SQL Server/T-SQL:如何更新结果集的相等百分比？

我需要一种方法来获取KeyID的结果集，并将其尽可能平均地划分，并根据KeyID对每个部门的记录进行更新。换句话说，有

SELECT KeyID
FROM   TableA
WHERE (some criteria exists)

我想通过3个相等的KeyID部分以3种不同的方式更新TableA。

UPDATE TableA
SET    FieldA = Value1
WHERE  KeyID IN (the first 1/3 of the SELECT resultset above)

UPDATE TableA
SET    FieldA = Value2
WHERE  KeyID IN (the second 1/3 of the SELECT resultset above)

UPDATE TableA
SET    FieldA = Value3
WHERE  KeyID IN (the third 1/3 of the SELECT resultset above)

或类似的东西。感谢您的所有回复。

最佳答案

With TiledItems As
    (
        Select KeyId
            , NTILE(3) OVER( ORDER BY ... ) As NTileNum
        From TableA
        Where ...
    )
Update TableA
Set FieldA = Case TI.NTileNum
                    When 1 Then Value1
                    When 2 Then Value2
                    When 3 Then Value3
                    End
From TableA As A
    Join TiledItems As TI
        On TI.KeyId = A.KeyId

关于sql - SQL Server/T-SQL:如何更新结果集的相等百分比？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/2804694/