When you're installing Ops Center, you have two options for the product database: You can use an embedded database, that's automatically installed on the Enterprise Controller and managed by Ops Center, or you can use a remote database that you manage yourself.
With regards to the customer-managed database, I saw an important question recently: When you install this database, do you have to enable any of the advanced or special features? Some folks want to use the bare minimum installation for security reasons.
The answer here is that Ops Center only requires the base installation; no special features are used. As long as you're using one of the DB versions listed in the Certified Systems Matrix, you're golden.