Object database for Java
I've recently got interested in object databases and would like to do my next project using ODB instead of a relational one. Now, since I'm completely new to them, it would be helpful if someone could recommend one to me. Can ODBs be queried with SQL or do they use a different system?
Please, don't be mad about this type of (barely-java-related) question. I did do some googling and discovered a few useful things (ie db4o), but I'd like a recommendation since I need something easy to adopt as I've alreadu started coding my project.