A Customer table is often be related to an Invoice table, on a CustomerID field. Add both the Customer and Invoice tables to the Relationships window.
Access pops up a dialog box to confirm the relationship.
Check the Referential Integrity checkbox. You never worry about referential integrity problems between these tables again. In the same dialog box, are options for Cascading Update , and Cascading Delete . If you elect to check these boxes, referential integrity is maintained by updating or deleting data in the related table. For example, if you alter a Customer's ID, then all related records are updated to reflect the change.