What is used to maintain the integrity of relationships between tables?

Maintaining the integrity of relationships between tables is fundamentally achieved through the use of foreign keys. A foreign key is a field (or a collection of fields) in one table that uniquely identifies a row of another table. This establishes a link between the data in the two tables, ensuring that the values in the foreign key field correspond to valid entries in the primary key of the referenced table.

By implementing foreign keys, a database enforces referential integrity, meaning it prevents actions that would result in orphaned records or inconsistencies. For instance, if a record in a parent table is deleted, a foreign key constraint would prevent deleting that record if dependent rows in a child table exist, thus preserving the relationship between the two datasets.

While primary keys are crucial for uniquely identifying records within a table, their primary role is not to maintain relationships across multiple tables but to enforce uniqueness within the same table. Table constraints, which include both primary and foreign keys, ensure data validity and integrity but don't specifically regulate the relationships between tables as foreign keys do. Data redundancy does not contribute to maintaining relationships; instead, it often complicates data management and integrity.

Thus, the use of foreign keys directly addresses the need for maintaining integrity in relationships between tables, making it the