Is it possible to fetch unique dedicated Business Code for my clients registration?

You will have to elaborate more about your wished functionality.
Not everything is clear in your setup.

  1. Are all of the Business-Categories already predefined and included in a Business-Collection, or do the Business-Collection grow-up with every NEW Business (entered by a new USER) automaticaly?

  2. What exactly would be the “Business-Sub-Categories”?

  3. The same question for “Business-Code” - - > It’s already predefined somewhere? Every of the Business has already a predefined CODE in a Collection, or do you generate always a NEW-RANDOM one for every new entered Business, which is not inluded in your Business-Collection, yet?

If you are searching for a good and exact answer, you should also elaborate more of your project and also give some more details, or the best would be a simple EXAMPLE of the whole project flow, from A to Z, described step by step!