GMetrix Data Modeling Practice Test

A foreign key is a link that ties two tables together. It is an attribute (or a set of attributes) in one table that points to the primary key (or another unique key) in another table, establishing a relationship between the two tables. This link enforces referential integrity, meaning every value in the foreign key must correspond to a valid row in the related table. Because of this connection, you can join the tables in queries and keep related data consistently connected. The other descriptions refer to different concepts: the attribute that uniquely identifies a row in the same table is a primary key; the attribute that ensures uniqueness in a column is a unique key or constraint; and storing derived data describes computed attributes, not a linking mechanism between tables.