ALTER TABLE chicken ADD CONSTRAINT chicken REFegg FOREIGN KEY (e ID) REFERENCES egg(e ID) INITIALLY DEFERRED DEFERRABLE; ALTER TABLE egg ADD CONSTRAINT egg REFchicken FOREIGN KEY (c ID) REFERENCES chicken(c ID) INITIALLY DEFERRED DEFERRABLE; In general, Oracle returns an error message when a constraint is violated.
To learn whether and in what ways the columns of an inherently updatable view can be modified, query the USER_UPDATABLE_COLUMNS data dictionary view.
The information displayed by this view is meaningful only for inherently updatable views.
Information on SQL constraints can be found in the textbook.
The Oracle implementation of constraints differs from the SQL standard, as documented in Oracle 9i SQL versus Standard SQL.
The object privileges to the schema objects referenced in the trigger body must be granted to the trigger owner explicitly (not through a role).