I'm pretty obsessed with WebSockets right now, and the way I would personally do that would be using Websockets to connect to an external server and have that communicate with a database.
However, a much simpler way would be to use PHP code. You will have to write it from scratch, but PHP does give you some methods to help connecting to the database. It's how PHPMyAdmin works (hence PHP).
There is an example in the tutorial section on how to make a chat application with a MySQL database, you can easily adapt that to your own needs. All it takes is a little knowledge of Structured Query Language Statements, like "SELECT * FROM table WHERE ID=1" (Select all the users from this table that have 1 as their ID number).
Oh, and by the way, PHPMyAdmin is not actually a database. MySQL is the database that PMA connects to. So PMA is just a database client. Also, for aproject like this, I would use MySQL instead of something like Microsoft SQL Server. MySQL is much easier to use.
Hope this helps :) Let me know if you need any other advice/help :P