Hi aq_sps and welcome to our forum,
Great question. The problem is that InfoPath doesn't support SQL query statements that refer to fields in your form. We have a Web service tool that we will beta release in a few days that will solve your problem. If you want to be a beta-tester, go to our About Us and fill out the Contact Us form. We'll send you a version. Cheers!
Patrick Halstead
Project Manager at Qdabra