Referential Actions
Because the database management system enforces referential constraints, it must ensure data integrity if rows in a referenced table are to be deleted (or updated). If dependent rows in referencing tables still exist, those references have to be considered. SQL:2003 specifies 5 different referential actions that shall take place in such occurrences:
- CASCADE
- RESTRICT
- NO ACTION
- SET NULL
- SET DEFAULT
Read more about this topic: Foreign Key
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“However, our fates at least are social. Our courses do not diverge; but as the web of destiny is woven it is fulled, and we are cast more and more into the centre. Men naturally, though feebly, seek this alliance, and their actions faintly foretell it.”
—Henry David Thoreau (1817–1862)