Certified Information Systems Security Professional (CISSP) Practice Exam

The role of a foreign key in a relational database is primarily focused on enforcing data integrity and referential integrity, which is fundamental in maintaining the relationships between tables. A foreign key is a field (or a collection of fields) in one table that uniquely identifies a row of another table or the same table. This represents a relationship between the two tables, allowing queries to join them together.

When a foreign key is set, it ensures that the value in this field must exist among the primary key values in the related table. This creates a link that validates that any entry in the child table correlates correctly to an existing entry in the parent table. This enforcement of valid connections between tables prevents orphaned records and maintains the integrity of the data across the database.

While the correct choice does mention the matching of a primary key in a related table, it is the aspect of having a foreign key that facilitates enforcing data consistency and referential integrity that tends to be the core purpose and benefit in relational databases. This essential role helps to maintain a structured and reliable data environment.