如何在mySQL查询中过滤掉重复的行

Question

我的初始查询（从employee_id按tbl顺序选择*）返回以下内容：

employee_name   Dept_Code   Supervisor          Date
John              99213     Mike              2013-01-10
John              99213     Dan               2013-12-13
John              99214     Kelly             2013-12-10
John              99215     Tammy             2013-09-09
Nancy             99244     Roy               2013-05-07
Nancy             99213     Cory              2013-04-05
Nancy             99214     Donald            2013-04-19
Nancy             99243     William           2013-07-01
Nancy             99244     Nick              2013-06-03
Rich              99203     Amber             2013-04-12
Dawn              99213     Nelson            2013-11-06
Rob               99213     Henrey            2013-08-01
Lewis             99213     Eric              2013-12-02
Alex              99203     Chris             2013-08-08
Alex              99243     Frank             2013-09-25
Bing              67228     Paula             2013-12-17
Bing              92225     Paula             2013-11-19

我只想使用max（Date）返回employee_name，Dept_Code和Supervisor。但是，当我运行以下。我的结果是一样的。

SELECT  employee_namd ,
        Dept_Code ,
        Supervisor ,
        MAX(Date) AS 'Date'
FROM    tbl
GROUP BY employee_name ,
        Dept_Code ,
        Supervisor
ORDER BY employee_name 

我只想看到：

employee_name   Dept_Code   Supervisor         Date
John              99213      Dan              2013-12-13
Nancy             99243      William          2013-07-01
Rich              99203      Amber            2013-04-12
Dawn              99213      Nelson           2013-11-06
Rob               99213      Henrey           2013-08-01
Lewis             99213      Eric             2013-12-02
Alex              99243      Frank            2013-09-25
Bing              67228      Paula            2013-12-17

Answer 1

;WITH Latest
AS
 (
  SELECT *,
     RN =  ROW_NUMBER() OVER (PARTITION BY employee_name ORDER BY [Date] DESC)
  FROM TABLE_NAME
 )
SELECT employee_name   
      ,Dept_Code   
      ,Supervisor  
      ,[Date]
FROM Latest
WHERE RN = 1