DISTINCT与CAST和GROUP BY

Question

我试图得到一个DISTINCT列,FeedbackDT但我似乎无法弄清楚为什么它不起作用..

SQL查询:

SELECT COUNT(FeedbackID) as FeedbackID,
       (SELECT DISTINCT CAST(feedbackDateTime AS DATE)) as FeedbackDT
FROM Feedback
WHERE feedBackDateTime <= GETDATE()
GROUP BY (feedbackDateTime)

执行查询的结果

我搜索高低,但无济于事..

感谢任何帮助,谢谢..

Answer 1

因为您当前的查询没有多大意义.使用时GROUP BY,您将获得要分组的列的不同值(如果使用多个列,则获取列的组合).SELECT DISTINCT您不需要使用子查询.

在我看来,你需要使用一个简单的GROUP BY:

SELECT CAST(feedbackDateTime AS DATE) FeedbackDT,
       COUNT(FeedbackID) as FeedbackID
FROM Feedback
WHERE feedBackDateTime <= GETDATE()
GROUP BY CAST(feedbackDateTime AS DATE)
;