Database is created at first scan of your files. So, you need to click on Scan function in menu, chose the root folder of your content files, let the iGOView scan it (it takes 10 minutes for my files), and Query should work after that.
Database function is not finished, it is just an experiment at the moment. I'll do some more work here for next release.
Main idea is to use the database to create complete Content kits. This will be more user friendly in the future.