只有當另一列也相同時纔可以使用ROW_NUMBER（）OVER/PARTITION BY？

Question

我使用此代碼：（從這樣一個問題：How to get the last record per group in SQL代我自己列）

WITH e AS 
(
SELECT *, 
    ROW_NUMBER() OVER 
    (
     PARTITION BY ApplicationId 
     ORDER BY theDate DESC 
    ) AS Recency 
FROM [Event] 
) 
SELECT * 
FROM e 
WHERE Recency = 1 

是否有可能「分區」只有當兩個字段都是一樣的嗎？例如，我有這樣的數據：

ID  Name theDate 
123  John 01/01/2012 
123  John 01/02/2012 
123  Doe  01/01/2012 
456  Smith 02/04/2012 
789  Smith 02/01/2012 
789  Smith 02/09/2012 
789  Roger 02/08/2012 

從這些數據我想回：

ID  Name theDate 
123  John 01/02/2012 
123  Doe  01/01/2012 
456  Smith 02/04/2012 
789  Smith 02/09/2012 
789  Roger 02/08/2012 

感謝您的幫助。

托馬斯

Answer 1

，我找到了答案在這裏分開：Table partitioning using 2 columns

只能對1列分區，但該列可以生成如下所示的「多分區」：

WITH e AS 
( 
SELECT *, 
ROW_NUMBER() OVER 
( 
    PARTITION BY CONVERT(VARCHAR(100),ApplicationId) + ' ' + Name 
    ORDER BY theDate DESC 
) AS Recency 
FROM [Event] 
) 
SELECT * 
FROM e 
WHERE Recency = 1 

將兩個列一起添加爲一個單一字符串，確保只有在兩列完全相同時纔會進行分區。

Answer 2

可以有多個列由逗號

WITH e AS 
( 
SELECT *, 
    ROW_NUMBER() OVER 
    ( 
     PARTITION BY ApplicationId , Name 
     ORDER BY theDate DESC 
    ) AS Recency 
FROM [Event] 
) 
SELECT * 
FROM e 
WHERE Recency = 1