查看計數列，並將值從單行轉換爲多行

Question

我在SQL Server 2008中有這個表T，我需要創建一個視圖，將每行的結果轉換爲多行。以下是目標視圖的示例。

請幫

當前表T

EmpID EmpName State City 
--------------------------------- 
1234 aaaa  NY  NY 
6789 bbbb  FL  Orlando 

目標視圖：

EmpID ColumnName  ColumnValue 
----------------------------------- 
1234 EmpName   aaaa 
1234 State   NY 
1234 City   NY 
6789 EmpName   bbbb 
6789 State   FL 
6789 City   Orlando 

Answer 1

CREATE VIEW yourView AS 
SELECT EmpID, 'EmpName' AS ColumnName, EmpName AS ColumnValue 
FROM T 
UNION ALL 
SELECT EmpID, 'State', State 
FROM T 
UNION ALL 
SELECT EmpID, 'City', City 
FROM T 

然後提供訂貨時，你實際上是從該視圖中選擇：

SELECT t.EmpID, t.ColumnName, t.ColumnValue 
FROM yourView t 
ORDER BY t.EmpID, 
     CASE WHEN t.ColumnName = 'EmpName' THEN 1 
       WHEN t.ColumnName = 'State' THEN 2 
       WHEN t.ColumnName = 'City' THEN 3 END