Confirming info in Database upon Form Insertion

We have a user portal on our site that allows users to upload photos. They register with us, then we send them a Group Code so that other users can join their portal and upload photos to share with others. Is there a way with the Web Assist plugins to cause the form to search for the Group Number they enter and validate that it's a legit Group Number already set up in the database. right now they can submit any value and register as a user, but I would it to block their registration unless they have a valid Group Number. I tried looking for a tutorial but didn't find what I think I'm looking for...

There isn't a built in feature of the extensions that will allow you to do this. You could create a recordset using the group id to filter the recordset and then check if the recordset is empty or not. Then if its empty don't execute the insert. You can use the built in Dreamweaver functionality for the show if recordset is empty/is not empty to display the errors or the inserted results. This would all be done on the page that is posted to after the form is submitted.