Wordpress Pre-approval table lookup for registration

Question

For our community band, I've created a table of Paid Members that I'd like to use as a lookup to restrict access to the registration form for the Members Area of our WordPress site. In other words, I'd like to do a lookup to the Paid Members table in the database and only let those in that table be able to get to the user registration page.

I'm new to WordPress, but had this working in jscript with compactSQL on an older MVC site. Thanks for any help pointing me in the right direction.