Does anyone know of a simple tutorial that explains how table joins work? I want to understand what actually happens in MySQL when you do a table join. In particular I want to know more about LEFT JOINs. It will make it a lot easier to understand how to use joins if I know what happens when you do one!

Devshed has an article , but it is kind of confusing. Kevin's book makes a good start on it, but I'd like an article that describes it a little more.