Contest Registration Form with Random winner generation

My Client needs a contest registration web page. Once per month he will start a new contest. People will go to the webpage, fill out the contact form, and be entered into a database, only accessible by my client. When the registration period is ended, he needs to have the system pick a random winner from among the database, and then he needs to be able to clear the registration list for the next contest. I don't care how it's built, what systems are used, or how it will end up working. My interest is how quickly i can get this done, and how easily i can implement into a simple css-based design that i've already completed. thank you, -Andrew