sql - SQL Server 按顺序分组

Question

我有一个表，我需要根据用户 ID 拉回 5 个最近的记录并关闭 documentID（无重复）。基本上，我正在跟踪访问过的页面并试图拉回用户最近的 3 个页面。

样本数据：

╔══════════════════════════════════════════════╗
║UserID   DocumentID   CreatedDate             ║
╠══════════════════════════════════════════════╣
║  71         22       2013-09-09 12:19:37.930 ║
║  71         25       2013-09-09 12:20:37.930 ║
║  72          1       2012-11-09 12:19:37.930 ║
║  99         76       2012-10-10 12:19:37.930 ║
║  71         22       2013-09-09 12:19:37.930 ║
╚══════════════════════════════════════════════╝

如果 UserID = 71，所需的查询结果：

╔══════════════════════════════════════════════╗
║UserID    DocumentID  CreatedDate             ║
╠══════════════════════════════════════════════╣
║  71         25       2013-09-09 12:20:37.930 ║
║  71         22       2013-09-09 12:19:37.930 ║
╚══════════════════════════════════════════════╝

Answer 1

SELECT TOP 3 UserId, DocumentId, MAX(CreatedDate)
FROM MyTable
WHERE UserId = 71
GROUP BY UserId, DocumentId
ORDER BY MAX(CreatedDate) DESC

Answer 2

您可以尝试使用CTE和ROW_NUMBER。

就像是

;WITH Vals AS (
    SELECT UserID, 
           DocumentID, 
           ROW_NUMBER() OVER(PARTITION BY UserID, DocumnentID ORDER BY CreatedDate DESC) RowID
    FROM MyTable
)
SELECT TOP 3 *
FROM Vals
WHERE UserID = 71
AND RowID = 1

Answer 3

你可以试试这个：

SELECT DISTINCT USERID, 
                DOCUMENTID, 
                MAX(CREATEDDATE) 
                  OVER ( 
                    PARTITION BY USERID, DOCUMENTID) CREATEDDATE 
FROM   MYTABLE 
WHERE  USERID = 71 

查看SQL Fiddle上的工作示例。

祝你好运！

Answer 4

Select USERID,DOCUMENT ID 
FROM yourtable
QUALIFY ROW_NUMBER OVER(Partition by user id ORDER By document id Desc)<6

这适用于 Teradata。希望这也适用于 Sql Server，因为它主要是 ANSI SQL。