text: BEGIN;
  
  ALTER TABLE artist
  DROP CONSTRAINT group_type_implies_null_gender;
  
  ALTER TABLE artist
  ADD CONSTRAINT group_type_implies_null_gender CHECK (
    (gender IS NULL AND type IN (2, 5, 6))
    OR type NOT IN (2, 5, 6)
    OR type IS NULL
  );
  
  COMMIT;
  