To identify 'you from others' you will need to store a bit of info. Traditionally you will generate a unique session ID for a user that allows you to map that unique session ID to any data you want. You usually just store the session ID in the cookie and store the data on the server in some sort of persistent store - you have MySQL so that is as good as anything. This is one way to maintain state across the stateless HTTP protocol. Super search for 'session management' or similar to see lots of examples.

CGI::Session may be what you are looking for.