SQL Server 中的 SUM 总时间 [英] SUM total time in SQL Server

问题描述

我对 SQL Server 中的 SUM 运算符有疑问.当我写这个查询时:

I have a problem with the SUM operator in SQL Server. When I write this query:

SELECT StudentID, StudentName, SUM(time) as 'TotalTime' 
FROM WorkNote
GROUP BY StudentID, StudentName

我收到此错误:

求和运算符的操作数数据类型时间无效.

Operand data type time is invalid for sum operator.

SUM 有没有其他方法或从记录中计算总次数?

Is there some other method for SUM or to calculate the total times from the records?

在我的WorkNote表中，time列的类型是Time(7)，我想SUM每个学生的所有(总)时间.

In my WorkNote table, the type of column time is Time(7), and I want to SUM all (total) times for every student.

推荐答案

如果时间在hh/mm/ss then ::

if the time in hh/mm/ss then ::

SELECT studentid,studentname,
         DATEADD(ms, SUM(DATEDIFF(ms, '00:00:00.000', mytime)), '00:00:00.000') as time
    FROM
         worknote

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