Your enterprise has created a database and database application.

The database designer tests the software because he or she is able to make necessary changes to the underlying code for the software.

A user who has no knowledge of the softwares underlying code tests the software.

Someone other than the database designer tests the software. This person has no access to the underlying code and attempts to use the software only in ways not considered by the software designers.

A person tests the software and submits suggestions to the software's underlying code. This person is someone other than the database designer, but has access to the softwares underlying code.