Referential Integrity in SQL/92

• SQL/92 supports all 4 options on deletes and updates.

  • Default is NO ACTION (delete/update is rejected)
  • CASCADE (also delete all tuples that refer to deleted tuple)
  • SET NULL / SET DEFAULT (sets foreign key value of referencing tuple)

CREATE TABLE Enrolled

(sid CHAR(20),

cid CHAR(20),

grade CHAR(2),

PRIMARY KEY (sid,cid),

FOREIGN KEY (sid)

REFERENCES Students

ON DELETE CASCADE

ON UPDATE SET DEFAULT )

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