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:
“The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it.”
—Jean-Jacques Rousseau (1712–1778)