Which key relationship uses a pointer from one table to indicate a relationship with another table?

The concept of a foreign key is essential to understanding relational database structures. A foreign key is a field (or a collection of fields) in one table that uniquely identifies a row of another table. It establishes a relationship between the two tables and allows for joining records from different tables, which is a fundamental feature of relational databases.

When a foreign key is utilized, it provides a link between the data in two tables, ensuring that the data in the foreign key field corresponds to a primary key in the referenced table. This relationship maintains referential integrity, enforcing rules about how records in these tables correlate with one another. For example, in a simple relational database, an "Orders" table might use a customer ID as a foreign key to relate to a primary key in a "Customers" table, ensuring that every order is linked to an existing customer.

Other key terms presented in the choices, like primary keys, are mainly used to uniquely identify a record in a table, while composite keys are a combination of two or more fields to form a unique identifier for a record. A secondary key is utilized for creating additional access paths to data but does not primarily establish relationships between tables. Consequently, the role of the foreign key is vital for defining relationships in relational databases