need apostrophe solution

i need to escape all my apostrophes in values submitted to a mySQL database. i know how to do the string replace, but is there a way i can loop thru all the post variables and replace the apostrophes? if so, do i need to refer to my variables like "$_POST[$variable]" instead of simply "$variable" (like i have currently) for it to work? any help would be greatly appreciated... -Doug