Someone submitted this through the suggestion form and i tried it -- very fun and cool.
Great way to learn a little sql database stuff. You learn while you manipulate the universe
Cross platform runs on windows and mac and source code is available.
Follow the instructions by your virtual teacher. The teacher can understand several possible mistakes that you may make, and gives hints on what may have gone wrong. You can skip to any chapter in the tutorial whenever you want.
Use the query editor to interact with the database, and to complete the assignments given by the virtual teacher. In case of syntax errors, SQLite (the database engine used in GalaXQL) returns helpful, human-readable error messages.
Author seems like a cool guy too and there are lots of other fun things on his website, including an active blog: http://sol.gfxile.net/index.html
From the last lesson in the program: "Also, send the author some mail! One of the biggest motivations for writing free software like this is getting comments from people, and it's always nice to hear when people find your programs to be useful."
So if you use the program send him an email and say hello (contact button is in upper right on blog page)