在Inner Join Sql Server期间删除重复的列值

Question

我有两张桌子

表1

EmployeeId  EmployeeName
    1            A

表2

EmployeeId  Month
    1        Jan
    1        Feb
    1        Mar
    1        Apr

当我根据employeeid应用内部联接时，我会得到这样的结果

EmployeeId  EmployeeName    Month
    1            A           Jan
    1            A           Feb
    1            A           Mar
    1            A           Apr

我想从表-1中删除所有重复的列值。我的结果应该是这样的。

EmployeeId  EmployeeName    Month
    1            A           Jan
                             Feb
                             Mar
                             Apr

请就此提出任何建议。

Answer 1

这就是工作：

WITH CTE AS
(
  SELECT t1.EmployeeId AS t1EmployeeID, t1.EmployeeName,
         t2.EmployeeId AS t2EmployeeID, Month,
         RN = ROW_NUMBER() OVER (Partition BY t1.EmployeeId 
                                 ORDER BY MONTH(t2.Month + ' 1 2015'))
  FROM Table2 t2
  LEFT OUTER JOIN Table1 t1
  ON t1.EmployeeID = t2.EmployeeID
)
SELECT EmployeeId = CASE WHEN RN = 1 
                    THEN t1EmployeeID ELSE NULL END,
       EmployeeName = CASE WHEN RN = 1 
                    THEN EmployeeName ELSE NULL END, 
       Month
FROM CTE

棘手的部分是按月缩写的月份名称。

Demo