Subcontractors: How do you locate them to consider hiring them?

This is a bit of a trick question. But how do other companies use JDE to find specific type vendors for subcontract work?

What I'm getting at is: If I wanted to look in JDE to see the subcontractors we've used in the state of Illinois in the past for consideration for my current job / project, how do I find them?

How do I find all of my plumbers? All of my masons? etc. As a technical person, I can run queries to get this information. But how would users who need to generate subcontracts / purchase orders find them to choose one?