If I request a unique number in my jotform, can I pre-populate fields based upon an SQL database with that information?

For instance:

User provides their name and unique number

subsequently the applicable fields in the form such as address and phone number are automatically filled from the DB link.

Hello AASRForms,

Unfortunately it is not possible to populate form fields from any data base, external source or previous submission data. 

Please note that with a little workaround it is possible to achieve your requirement but that will require additional programming to post the form data to your own page where you can read the unique id of form and fetch the data from database. You may like to take a look at the following guide on how to post form data to your own page:  https://www.jotform.com/help/51-How-to-Post-Submission-Data-to-Thank-You-Page

Thank you!