SUM total time in SQL Server [duplicate]

Question

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

I get this error:

Operand data type time is invalid for sum operator.

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

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

Answer 1

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