Logging In Pull More Info

this is a continuation of my little login page I am setting up.
the login pages authenticates the user using Active Directory.
I also have a Database locally in MSSQL that has the users ref number (primary key, incrementing) first name, last name, and user id (same user id as ldap/AD etc)
what I want to do is when the user logs in the page will call the Database and grab the full name as well as the ref number. Later in the page if the user submits a form to add data to another database I want it to populate a column in a table using the ref number. that should be rather easy once I actually have that ref number.so how would I tell the page to go to my database and grab his ref number (as well as his name to be able to display Welcome first Lastname instead of userid?