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Propagation constraint

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This is an old revision of this page, as edited by Elwikipedista~enwiki (talk | contribs) at 02:11, 11 October 2005 (Links & ==Bibliography==). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

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.
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