what project would be good for beginners? [opinions needed]

I'm planning on making system.
Can anyone give me something that would be not too easy but not too difficult... maybe for beginners
I want to make a system with GUI and database as a part of my learning process :)

hope to hear some feedbacks

Here's a link to a search I did earlier for another thread about creating a GUI-fronted database application with netbeans:

netbeans java db

You don't say what level of beginner you are. If you're a complete beginner, maybe you should consider delaying writing a 'system' and consider instead learning some features of the tools you're about to use:

Trail: Learning the Java Language (The Java™ Tutorials)

im already familiar with the java language but thanks for the link
not a complete beginner here