Question

请帮我查询一下。假设我们有一个包含列的表：

交易
StartTime
结束时间

现在，我需要一个带有计算列的查询（value = EndTime-Startime）。实际上我需要对用户进行分组（交易有用户的FK）并按平均交易时间对它们进行排序。

Answer 1

SELECT u.userid
       ,AVG(DATEDIFF(second, StartTime, EndTime) AS AvgTime
FROM trxn AS t
INNER JOIN users AS u
    ON trxn.userid = u.userid
GROUP BY u.userid
ORDER BY AVG(DATEDIFF(second, StartTime, EndTime)

Answer 2

您应该查看DateDiff函数。你没有指定时间跨度的单位，所以我在我的解决方案中假设秒数：

Select ...
From dbo.Users As U
    Join    (
            Select T.UserId, Avg( DateDiff(s, T.StartTime, T.EndTime) ) As AvgTimespan
            From dbo.Transactions As T
            Group By T.UserId
            ) As Z
        On Z.UserId = U.Id
Order By Z.Timespan Desc

带有计算列的SQL查询

2 个答案: