Chatroom problems

I've built a chatroom in PHP : mySQL, which is working perfectly. Only problem is, once the user has gone form the chatroom after chatting, his records are not deleted. Anyone who ever enters the chat, his records are always there in the database even after he's left. And since the screen always shows the last 18 statements, pretty old statments are always there and the "Online Users" also has the name of someone who's left. HOw do i do this? I mean, how do i erase his records once he's left? What i need is some kind of script which checks after one or two hours if there's any activity pertaining to that name or something and if unactive than delete all rows matching that name criteria.... any suggestions... Regards, Rahul S. Johari ===== Rahul S. Johari (Director) ****************************************** Abraxas Technologies Inc. Homepage : http://www.abraxastech.com Email : abraxastech@yahoo.com Tel : 91-4546512/4522124 ******************************************* __________________________________________________ Do You Yahoo!? Yahoo! Photos - Share your holiday photos online! http://photos.yahoo.com/