What is the primary function of a foreign key in a relational database?

The primary function of a foreign key in a relational database is to create relationships between different tables. A foreign key is a specific field (or a collection of fields) in one table that refers to the primary key in another table. This linkage is integral to the relational database model, as it establishes a connection between related data stored across multiple tables, enabling more complex queries and maintaining data integrity.

By using foreign keys, databases enforce referential integrity, ensuring that relationships between tables remain consistent. For instance, if you have a customer table and an orders table, the orders table would use a foreign key that references the primary key of the customer table to maintain the association between customers and their respective orders. This structural organization allows for efficient and logical data retrieval, reflecting the relationships inherent in the data model.

The other options do not align with the primary role of a foreign key. While deleting records or executing queries may involve foreign keys in some contexts, those are not their main purpose. Similarly, maintaining a record of primary keys does not capture the essence of how foreign keys function in establishing table relationships.