Wel, if you still want a webserver along with a database, you have a few options.
1. The webserver needs to stay on port 80. Find out what port the database uses. Configure your firewall rules to allow incoming connections to the database port from either the specific IP addresses, or a range of addresses, or whatever.
2. Run the database on a seperate machine if possible. Configure your firewall to pass all http traffic to your webserver, adn the database stuff to the DB machine.
3. I think you can get the point of this. Either way, you'll have to have 2 ports open - 1 port for yoru webserver, and the other for your database, whether they be on the same box or not.
When you start changing ports around for standardized protocols, you either have to have something in the middle of your servers and your clients to do the port redirection, or nobody will be able to connect.
Oh, and besides that, changing the port on your WEB server won't allow incoming traffic to your DATABASE. I'd highly recommend getting a book on Internet firewalls from O'Reilly so you can learn why that won't work, and what you can do to configure your servers to allow incoming connections to a webserver and your database.