Referential integrity in table relationships keeps users from accidentally deleting or changing related data. If a primary table contains a list of employees and related tables contain additional information about those employees , and an employee quits, his record is removed from the primary table. His records should also be removed in all related tables. Access allows you to change or delete related data, but only if these changes are cascaded through the series of related tables. You can do this by selecting the Cascade Update Related Fields and Cascade Delete Related Records check boxes in the Edit Relationships dialog box.
Ensure Referential Integrity