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:
“Can it be borne, this bodying-forth by wind
Of joy my actions turn on, like a thread
Carrying beads?”
—Philip Larkin (1922–1986)