Propagation constraint

According to Beynon-Davies (2004, p.108) [a] propagation constaint details what should happen to a related table when we update a row or rows of a target table . He further states that for all relationships, one should define how to handle deletions of target and related Tuples. There are three possibilities:

Restricted Delete - cannot delete the target row until all rows that point to it (via foreign keys) have been deleted.

Cascades Delete - can delete the target row and all rows that point to it (via foreign keys) are also deleted.

Nullifies Delete - can delete the target row and all foreign keys (pointing to it) are set to null.

=Bibliography=

*Beynon-Davies, P. (2004) Database Systems Third Edition, Palgrave.