From the Help file:
referential integrity
Rules that you follow to preserve the defined relationships between tables
when you enter or delete records. If you enforce referential integrity,
Microsoft Access prevents you from adding records to a related table when
there is no associated record in the primary table, changing values in the
primary table that would result in orphan records in a related table, and
deleting records from the primary table when there are matching related
records in a related table.
The "how" is create a relation between two tables and select that you want
to enforce referential integrity.
