Referential Integrity

child table (FK): can you update values?

1. yes if a corresponding new PK exists.

parent table (PK): can you update values?

1. yes if there are no FK's 2. yes if ON UPDATE CASCADE is on

parent table (PK): can you delete values?

1. yes if there are no FK's 2. yes if cascade delete is implemented 3. yes if ON DELETE SET NULL is on

child table (FK): can you insert new values?

1. yes if theres a corresponding PK 2. yes if FK is set to Null

how is referential integrity implemented?

Referential integrity constraints are implemented with foreign key to primary key references.

parent table (PK): can you insert new values?

anytime

referential integrity

rule states that any foreign key value (on the relation of the many side) MUST match a primary key value in the relation of the one side. (Or the foreign key can be null)

child table (FK): can you delete values?

yes