Question

Hello, I am in the need to do the following: A web form in which A user clicks on a timer button. The after a certian amount of time the click a end timer button and the time is logged to a mysql dbase. ANyone know how I could go about this. I was thinking I could store the start time in a cookie, and then when end timer button is pressed I could read the value from the cookie, write it, and then destroy the cookie. ANy ideas ? Thanks Jim