列出具有最近日期的行

Question

我有一個列出合同日期的表。合同可以有多個日期，所以我只想要最近的一個。

我試圖通過contractEnded日期排序，然後過濾，這樣我只得到了第一個排名，但我不斷收到一個語法錯誤：

無效的列名稱contractRank「。

SELECT MAX(contractEnded) AS contractEnded, contractID, contractStarted, contractEnded, userID, examID, 
ROW_NUMBER() OVER (
        partition by userID 
        ORDER BY MAX(contractEnded) desc) 
        AS contractRank 
FROM examcontract es 
WHERE examID = 92855231134 
and es.contractRank = 1 
GROUP BY userID, examID, contractID, contractStarted, contractEnded 

有沒有辦法在MSSQL 2012年做到這一點？

謝謝！

Answer 1

排名函數無法在查詢中使用，您將需要使用外部查詢來操作任何排名函數。

另外，您不需要使用MAX（）函數來獲取使用Ranking函數的最後日期，下面的查詢將返回表中每個用戶ID的Last Contract結束日期。

SELECT contractEnded, contractID, contractStarted, contractEnded, userID, examID 
FROM (
    SELECT contractEnded, contractID, contractStarted, contractEnded, userID, examID, 
     ROW_NUMBER() OVER (partition by userID ORDER BY contractEnded desc) AS contractRank 
    FROM examcontract 
    WHERE examID = 92855231134 
    )A 
WHERE A.contractRank = 1 

正如Aaron在您的評論部分中提到的，您也可以使用CTE（公用表表達式）來實現相同的結果。

;WITH CTE AS 
(
    SELECT contractEnded, contractID, contractStarted, contractEnded, userID, examID, 
    ROW_NUMBER() OVER (partition by userID ORDER BY contractEnded desc) AS contractRank 
    FROM examcontract es 
    WHERE examID = 92855231134 
) 
SELECT contractEnded, contractID, contractStarted, contractEnded, userID, examID 
FROM CTE 
WHERE contractRank = 1