When you need to understand a new database schema, making a model like this is a big help. I still like DBDesigner4 fromfabFORCE.net to get these simple models done. Yes, I know there's a much newer GUI program, MySQL Workbench, that could do a better job. One day I'll have time to test you again, Workbench. But for me, DBDesigner4 is a simple yet powerful tool.