How to count time in Time fields?

Question

SQL

The table has a start and end time field. There can be multiple entries for one day. It is necessary to calculate the time how many people worked in the specified period.
So far, I'm only considering the option, through arrays in C ++ and a lot of queries to the MS SQL DBMS.

Answer 1

what's wrong with classic datediff ? it is possible even at once the calculated field to make.