SQL SUM（）函数忽略WHERE子句和CASE语句

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

The preceding SQL query returns the correct "Number of Calls" but the "Total Time" and "Average Time" are always the same regardless of the # of calls (which is obviously wrong).

I've read and tried to implement using the CASE WHEN __ Then value ELSE 0 inside SUM but it still returns an incorrect value.

The only way I can get this query to return correct results is if I completely strip out all other info, eg

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

How can I still use my JOIN and GROUP BY and get the aggregate functions to give me the results I want?

Thanks for any and all help!

Answer 1

您可能最好使用子查询，例如在SELECT部分​​中，添加类似(SELECT SUM(...) FROM ... WHERE ...) AS total_sum 。