Hi,
i must prevent a record delete and update if the primary key of this record
are "used" into another table.

For prevent the delete i can set a ForeignKey constraint into the other
table with the clause ON DELETE NO ACTION but how i can prevent the field
UPDATE ?
If i use the constraint only the UPDATE on primary key are controlled and
not all the other fields.
In my client application i can protect the other field (setting all edit
components in read-only mode) but i need to test if the are some constraint
that i must respect.

Anyone have some idea?

Best regards,
Enrico Raviglione.