Referential Integrity

Referential integrity preserves the defined relationships between tables when records are added or deleted. Referential integrity is based on foreign to primary key or unique key relationships and ensures that key values are consistent. This consistency requires that there are not references to nonexistent values, and that if a key value changes, all references to it change consistently throughout the database.

When referential integrity is enforced, the database prevents users from:

• Adding records to a related table when there is not an associated record in the primary table.

• Changing values in a primary table that would result in "orphaned" records in a related table.

• Deleting records from a primary table when there are matching related records.