選擇從同一個表的多個行的不同列一列的值

Question

我有一個表，定義如下：

CREATE TABLE [dbo].[Due] (
[dueID]   INT   IDENTITY (1, 1) NOT NULL, 
[dueTypeID]  INT   NOT NULL, 
[vehicleID]  INT   NOT NULL, 
[dueDate]   DATE   NULL, 
... 

在這裏，我想生成一個查詢，這將使輸出作爲

VehicleID Type1.dueDate Type2.dueDate Type3.dueDate ... 

（到期日應該是最高的爲車輛，由於類型）

我寫了下面的查詢做到這一點：

select vehicleNumber, A.dueDate, B.dueDate, C.dueDate, D.dueDate, E.dueDate, F.dueDate 
FROM Vehicle INNER JOIN 
(SELECT Max(dueDate) as dueDate,vehicleID from Due where dueTypeID = '1' GROUP BY Due.vehicleID) As A ON Vehicle.vehicleID = A.vehicleID INNER JOIN 
(SELECT Max(dueDate) as dueDate,vehicleID from Due where dueTypeID = '2' GROUP BY Due.vehicleID) As B ON Vehicle.vehicleID = A.vehicleID INNER JOIN 
(SELECT Max(dueDate) as dueDate,vehicleID from Due where dueTypeID = '3' GROUP BY Due.vehicleID) As C ON Vehicle.vehicleID = A.vehicleID INNER JOIN 
(SELECT Max(dueDate) as dueDate,vehicleID from Due where dueTypeID = '4' GROUP BY Due.vehicleID) As D ON Vehicle.vehicleID = A.vehicleID INNER JOIN 
(SELECT Max(dueDate) as dueDate,vehicleID from Due where dueTypeID = '5' GROUP BY Due.vehicleID) As E ON Vehicle.vehicleID = A.vehicleID INNER JOIN 
(SELECT Max(dueDate) as dueDate,vehicleID from Due where dueTypeID = '6' GROUP BY Due.vehicleID) As F ON Vehicle.vehicleID = A.vehicleID 

問題是，沒有特定類型的到期日的車輛正在採取其他車輛的價值。請幫我弄清楚如何解決這個問題，如果我這樣做是正確的，還是有更好的方法來解決這個問題？

（不好意思的情況下，這個問題是重複的，因爲我試圖尋找，但沒有找到合適的關鍵字搜索問題）

非常感謝幫助我。

Answer 1

試試這個：

select vehicleNumber, 
    Max(case When dueTypeID = '1' Then dueDate Else null end) Typ1dueDate, 
    Max(case When dueTypeID = '2' Then dueDate Else null end) Typ2dueDate, 
    Max(case When dueTypeID = '3' Then dueDate Else null end) Typ3dueDate, 
    Max(case When dueTypeID = '4' Then dueDate Else null end) Typ4dueDate, 
    Max(case When dueTypeID = '5' Then dueDate Else null end) Typ5dueDate, 
    Max(case When dueTypeID = '6' Then dueDate Else null end) Typ6dueDate 
FROM Due d join Vehicle v 
    On v.vehicleId = d.vehicleId 
Group By v.vehicleNumber