For the crowd you describe I think the SQL tutorial at W3Schools is a good start (my 2¢). Like Jeff mentioned they have a "Try it yourself" section and they even have a little, 20-question test.
"I cant stress enough the importance of switching from a sequential files mindset to set-based thinking. After you make the switch, you can spend your time tuning and optimizing your queries instead of maintaining lengthy, poor-performing code."-- Itzik Ben-Gan 2001