Finding past 12 hrs from current time

[PHP_apprentice]

I am trying to display stats for files recieved in a DB. Two of the stats I would like to show are past 12hr and past 24hrs. I am having alot of difficulty with this can anyone direct me to a good function or give me an idea where to start.

[weekender]

[man]strtotime[/man] interprets english time commands

think you can do strtotime("-12 hours");

know you can do strtotime("-1 day");

adam