Local to new host based on existing site that I need to preserve

I am using a subdomain for site ‘A’ under development. I downloaded it and its db to local. Redesign etc. Now I want to go to host site as new subdomain so the existing stays intact.
My question, along with the files do I upload the db and keep the same db or is that a nono to share db with site ‘A’. If so what should I do exactly. Thanks in advance for any help