Sybase IQ provides protection against referential integrity loss.
updates or deletes a primary key value that has a matching foreign key value. All the foreign keys referencing that primary key would violate referential integrity.
adds a new row to the foreign table, and enters a value for the foreign key that has no corresponding candidate key value. The database would violate referential integrity.
When a referenced candidate key is updated or deleted, Sybase IQ disallows UPDATE or DELETE.