Referential integrity is a concept for ensuring that relationships between database tables remain consistent. The tables between which referential integrity must exist are called referenced tables and referencing tables.

Referential integrity is enforced by using foreign keys. A foreign key is a field in the referencing table that matches a primary key column (or other similar unique column) of the referenced table. The foreign key can be used to represent a conceptual relationship of the type 1-to-n, such as, “an employee belongs to a department”. For example, referential integrity ensures that if the referencing table has a foreign key to the referenced table, you cannot add a record to the referencing table unless there is a corresponding record in the referenced table.

Foreign keys are maintained with referential constraint definitions. The constraints specify what referential actions solidDB^® must take when the constraint is violated. This can happen, for example, when a row with a referenced primary key is deleted from the referenced table.