Question

    SELECT      u.FirstName + ' ' + u.LastName as 'User',
            COUNT(*) as 'Number of Calls',
            CONVERT(varchar(4), SUM(CASE WHEN c.FromTime BETWEEN @FromDate AND @ToDate
                THEN DATEDIFF(mi, c.FromTime, c.ToTime) ELSE 0 END) / 60) + ':' + 
            CASE WHEN SUM(CASE WHEN c.FromTime BETWEEN @FromDate AND @ToDate
                THEN DATEDIFF(mi, c.FromTime, c.ToTime) ELSE 0 END) % 60 < 10 THEN '0' ELSE '' END +
            CONVERT(varchar(2), SUM(DATEDIFF(mi, c.FromTime, c.ToTime)) % 60) as 'Total Time Spent',
            CONVERT(varchar(4), AVG(DATEDIFF(mi, c.FromTime, c.ToTime)) / 60) + ':' +
            CASE WHEN AVG(DATEDIFF(mi, c.FromTime, c.ToTime)) % 60 < 10 THEN '0' ELSE '' END +
            CONVERT(varchar(2), AVG(DATEDIFF(mi, c.FromTime, c.ToTime)) % 60) as 'Average Call Time'
FROM        Calls c
JOIN        Users u ON u.UserID = c.TakenBy
WHERE       c.FromTime BETWEEN @FromDate AND @ToDate
GROUP BY    u.UserID, u.FirstName, u.LastName
ORDER BY    u.FirstName + ' ' + u.LastName

前面的SQL查询返回正确的“调用次数”，但“总时间”和“平均时间”始终相同，无论调用次数多少（显然都是错误的）。

我已阅读并尝试使用CASE WHEN __然后在SUM内部对ELSE 0进行实现，但它仍然返回不正确的值。

我可以获得此查询以返回正确结果的唯一方法是，如果我完全删除所有其他信息，例如

SELECT SUM(DATEDIFF(mi, FromTime, ToTime)) FROM Calls WHERE c.FromTime BETWEEN...

我如何仍然使用我的JOIN和GROUP BY并获得聚合函数来给我想要的结果？

感谢您的帮助！

Answer 1

你可能最好使用子查询，例如在SELECT部分中，添加(SELECT SUM(...) FROM ... WHERE ...) AS total_sum。

之类的内容

SQL SUM（）函数忽略WHERE子句和CASE语句

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