Well, I see in the other thread that you are using PHP. There is a 3rd-party PHP library that implements a data source that you can use with the Query language (see it here:
http://code.google.com/p/mc-goog-visualization/wiki/UserDocumentation, docs have examples). If you don't want to use that, I'm not sure that there are any tutorials that will help you, but there are many threads on this forum that deal with the topic, and I can walk you through solutions.