Theme's and Databases Question

I’m assuming when you say ‘each theme’ you mean, a different site?

Have you checked out the Installing Multiple Blogs page?

Yes, I meant a different website.

From the documentation (Installing Multiple Blogs)

…if you need multiple WordPress instances, you must actually install each WordPress separately (that is, as a separate WordPress installation). System architecture can be divided into two types by number of databases.

1. Multiple databases installation. Each database manages specific site’s information.
2. Single database installation. The database manages all site’s information.

Thank you for the information:)