The key is an attribute or a group of attributes whose values can be used to uniquely identify an individual entity in an entity set. First Name and Last Name – assuming there is no one else in the co...The key is an attribute or a group of attributes whose values can be used to uniquely identify an individual entity in an entity set. First Name and Last Name – assuming there is no one else in the company with the same name The primary key is a candidate key that is selected by the database designer to be used as an identifying mechanism for the whole entity set. A foreign key (FK) is an attribute in a table that references the primary key in another table OR it can be null.
