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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“The legislative powers of government reach actions only, and not opinions, ... thus building a wall of separation between Church and State.”
—Thomas Jefferson (1743–1826)