I have a bunch of records in a MySQL database

Typically I would like to work out the amount of hours and minutes between 2 dates for each record in the database...

Code:
2010-01-01 00:00:00
2010-01-02 00:00:00

Is 24 hours.
and then add all of those together to get the total amount of hours to the nearest hour.

I am not used fluent in PHP and rarely use it, but now I'm a bit stumped ...

Thanks