Appendix

referential integrity

The technique of maintaining data always in a consistent format. In particular, data in different tables is kept consistent through the use of foreign key constraints, which can prevent changes from happening or automatically propagate those changes to all related tables. Related mechanisms include the unique constraint, which prevents duplicate values from being inserted by mistake, and the NOT NULL constraint, which prevents blank values from being inserted by mistake.

Parent/Child Tables

The parent is the table that contains the original key values.

The child is the related table that refers to key values in the parent.