mysql php date math (dateandtimeA - dateandtimeB)

Question

I am working on a time system where I need to take the time someone punches in to when some on punches out

i.e 2011-05-20 08:30:00 (punch in time) - 2011-05-20 17:30:00 = X hrs
or  2011-05-20 09:45:00                 - 2011-05-25 17:57:00 = X days Y hrs

Any help would be awesome!

Answer 1

Firstly: How to calculate the difference between two dates using PHP?

Then: http://www.php.net/manual/en/datetime.diff.php

In SQL: http://www.w3schools.com/SQl/func_datediff_mysql.asp