How do I see if a date range falls within or overlaps another date range?

How do I see if a date range falls within or overlaps another date range?

I'm trying to make a school register.

The teachers need to be able to print off a weekly sheet which shows on what days each student will be attending.

Technically, I think this boils down to seeing if one date range (the period of the student's attendance) falls within another date range (the period of the register - these are needed weekly).

Any help from anyone on how to do this would be greatly appreciated :)