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
Famous quotes containing the word actions:
“Men’s actions are too strong for them. Show me a man who has acted, and who has not been the victim and slave of his action.”
—Ralph Waldo Emerson (1803–1882)