SQL Access：每个ID的最近日期

Question

我有四个表：User，Version，VersionOfDocument，Document。 ER如下所示:(粗体=主键）

我希望查询为每个documentID显示最近的日期，versionNr以及最后一次更改文档的人：

documentID          modifiedDate    Username                  VersionNr
1                   1/4/2014        Alfred.Heymans@test.nl     2.0
2                   2/5/2013        Alfred.Heymans@test.nl     1.0
3                   4/5/2014        John.Smith@test.nl         2.0

Answer 1

试试这个：

SELECT VD.DocumentID, V.modifiedDate, U.Username, V.VersionNr
FROM VersionOfDocument VD 
INNER JOIN VERSION V ON VD.VersonId = V.VersionId 
INNER JOIN (SELECT VD.DocumentID, MAX(V.modifiedDate) modifiedDate
            FROM VersionOfDocument VD 
            INNER JOIN VERSION V ON VD.VersonID = V.VersionID 
            GROUP BY VD.DocumentID
           ) AS A ON VD.DocumentID = A.DocumentID AND V.modifiedDate = A.modifiedDate 
INNER JOIN USER U ON V.userID = U.userID;