Sane

MySQL is a relational database. That means it's used to store tables of information. It is not used to transfer information over network sockets.

You could use MySQL to distinguish who is who on the network... but if you're just trying to make an instant messenger for communal purposes, a public password and free-reign over usernames is all that's required (which requires no relational databases).

And if that is not the case, it is then important to note that setting the objective of programming a publicly accessable instant messenger which uses your own chat server, is quite an (overly) ambitious goal for a group of new programmers.

I don't mean to sound rude, but it might be important to note that this is more of a learning experience for new programmers. Is that correct? By not mentioning that, in my opinion, you're throwing away credibility in any thread that looks for new members-- Unless you do have some experts in your group that already know the difference between MySQL and networking. Then I would be incorrect, and your group would look more promising for making such things as instant messengers.