This help book is a sub-book to the Tables book covers the following information:

Referential integrity validates and updates the data in the linked key fields of a relational database.  In a relational database, a field or group of fields in one table (the child table) refers to the key of another table (the parent table).  Referential integrity rules ensure that only values that exist in the parent table’s key are valid values for the specified fields of the child table.