只有当另一列也相同时才可以使用ROW_NUMBER（）OVER/PARTITION BY？

Question

我使用此代码：（从这样一个问题：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“分区”只有当两个字段都是一样的吗？例如，我有这样的数据：

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 

从这些数据我想回：

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 

感谢您的帮助。

托马斯

Answer 1

，我找到了答案在这里分开：Table partitioning using 2 columns

只能对1列分区，但该列可以生成如下所示的“多分区”：

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 

将两个列一起添加为一个单一字符串，确保只有在两列完全相同时才会进行分区。

Answer 2

可以有多个列由逗号

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