Converting datatypes, not sure if this is the right direction?

New to developing. We are working on a project using asp.net and c# where data is pulled out of an sql database via multiple tables and displayed via a details view. The user can then update the information and submit it back to the database.

The problem we are encountering is:

Within the database there are multiple tables joined by a FK for example there is a Service Group ID column with the Records main table linked to the Service Group table which holds an ID column and a Service Group column so ID1 = Service Group A. Any records within the main table which has an ID of 1, is shows as Service Group A in the details view.

What we wold like to do is when a user updates the Service Group via a drop down, the ID goes into the main table rather than the Service Group name so if they select Service Group B, an ID of 2 goes into the Records main table. We aren't sure how to go about doing the conversion of Service Group B to an ID 2? We have been looking at converting datatypes but don't think it is right for what we are trying to do,

Any suggestions would be gratefully recieved Apologies if this is in the wrong forum.

thanks

mySQL or msSQL?
i think your in the wrong forum