选择日期的不同以及表格中的其他字段

Question

在'Emplyoee'表中有两个字段 - JoinDate和EmployeeName。

Emplyoee表中包含的所有数据如下：

JoinDate      | EmployeeName
------------------------
02-12-2009   Vijay

03-12-2009   Binoy

03-12-2009   Rahul

我的选择查询如下：

SELECT DISTINCT JoinDate,EmployeeName FROM Emplyoee

我得到的结果如下：

JoinDate   | EmployeeName
------------------------
02-12-2009   Vijay
03-12-2009   Binoy
03-12-2009   Rahul

但我需要的结果如下：

JoinDate   | EmployeeName
------------------------
02-12-2009   Vijay
03-12-2009   Binoy(first employee joined on this date)

Answer 1

这将选择在每个日期加入的第一个按字母顺序的员工：

 SELECT DISTINCT mydates.JoinDate, 
    (SELECT TOP 1 EmployeeName FROM Employee e2 WHERE e2.JoinDate=mydates.JoinDate ORDER BY EmployeeName)
 FROM Employee mydates