There is no possible way for us to tell what retailers use the data base and which do not. There isn't any formula to determine it and it's not limited to certain kinds of retailers. The whole point of the data base is that you don't know which ones are using it or not. All you can do is apply and find out.
Oh, and don't "forget" to take off the earrings you try on next time. You're not supposed to try them on in the store in any case.

