The access control models which are used here are physical access control, logical access control and database access control.
John is the database administrator and he grants his assistant privileges in line with his duty to create databases and other database objects. So there are the access control models which are used here.
Physical access control limits access to rooms, campuses, buildings, and IT assets. Logical access control limits connections to computer networks, system files and data.
Database access control, is a method of allowing access to a company's sensitive information only to user groups who are allowed to access such data.
Hence, the answer is given and explained above.
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