Question

我有一个包含文档ID列和日期列的视图以及与此问题无关的十几个其他列。可以有多个具有相同文档ID的行，但日期通常不同。这表示它是同一个文档，只是它的修订版。问题是如果我有两行文档ID和日期是相同的，我得到两个。我只想得到一个。无论哪一个，只要我得到一个。

以下内容与文档ID和日期相同有重复。

SELECT FSD.*
FROM vFSD FSD
INNER JOIN
    (
    SELECT InternalID, MAX(FileLastUploadedDate) AS FileLastUploadedDate
    FROM vFSD
    GROUP BY InternalID
    ) gFSD ON FSD.InternalID = gFSD.InternalID AND FSD.FileLastUploadedDate = gFSD.FileLastUploadedDate

我也尝试过DISTINCT，但它没有解决问题。

SELECT DISTINCT FSD.*
FROM vFSD FSD
INNER JOIN
    (
    SELECT DISTINCT InternalID, MAX(FileLastUploadedDate) AS FileLastUploadedDate
    FROM vFSD
    GROUP BY InternalID
    ) gFSD ON FSD.InternalID = gFSD.InternalID AND FSD.FileLastUploadedDate = gFSD.FileLastUploadedDate

Answer 1

您可以使用ROW_NUMBER仅在两个与FileLastUploadedDate

相同的最大InternalID绑定的情况下带回一个任意行

WITH CTE
     AS (SELECT *,
                ROW_NUMBER() OVER (PARTITION BY InternalID 
                                       ORDER BY FileLastUploadedDate DESC) AS RN
         FROM   vFSD)
SELECT InternalID,
       FileLastUploadedDate
       /*Other desired columns*/ 
FROM   CTE
WHERE  RN = 1

如果值相等，SQL Max将返回重复项

1 个答案: