如何在select查询中选择与max函数结果匹配的列的值

Question

我有一个表，该表具有与进行的用户测试有关的某些数据。我想从下表中获得max（testnumber）以及状态对应的max（testnumber）。

SELECT @LastAttemptedTest=MAX([TestNumber] FROM [dbo].[StudentChapterwiseTest] WHERE 
    [ChapterId]=584 AND [StudentId]=212045 

SELECT Status FROM [dbo].[StudentChapterwiseTest] WHERE [TestNumber]=@LastAttemptedTest AND
    [ChapterId]=584 AND [StudentId]=212045                                          

我试图在单个选择查询中获得max（testnumber）和状态对应于max（testnumber）的结果

Answer 1

您可以使用row_number()：

select t.*
from (select t.*, row_number() over (partition by studentid order by testnumber desc) as seq
      from table t
     ) t
where seq = 1;

编辑：：如果需要一行，请使用top (1)子句：

select top (1) t.*
from table t
order by t.testnumber desc;

Answer 2

在子查询中选择最大测试数，然后在该子表上加入

SELECT t.status, t.testNumber
FROM StudentChapterwiseTest t
JOIN (SELECT StudentId, ChapterId, MAX(status) as max_stat 
      FROM StudentChapterwiseTest
      GROUP BY StudentId, ChapterId) mt ON t.status = mt.max_stat  AND t.chapterId = mt.chapterid AND t.studentId = mt.studentid
WHERE [ChapterId]=584 AND [StudentId]=212045