UPDATE hedera.orderRow or2
 LEFT JOIN vn.sale s ON s.id = or2.saleFk
 SET or2.saleFk = NULL
 WHERE s.id IS NULL AND or2.saleFk IS NOT NULL;

ALTER TABLE `hedera`.`orderRow` 
ADD CONSTRAINT `orderRow_ibfk_4`
  FOREIGN KEY (`saleFk`)
  REFERENCES `vn`.`sale` (`id`)
  ON DELETE SET NULL
  ON UPDATE CASCADE;