When working with records in a set, if you change the values in either of the linking key fields, and do not make the same change in both the parent and related child records, the relationships between these records can be severed. To prevent this, you can use one of two types of referential integrity to manage the link.
Cascades changes from the parent linking key field to the child linking key field so that records that are related continue to be related. When you delete a parent record, all related child records are also marked for deletion. This ensure that child records that would make no sense apart from a matching parent record are not orphaned.
Prevents changes to the parent linking key field so that records that are related continue to be related.
For each link in a set, you specify either the referential integrity option you want to use, or that no referential integrity should be enforced.