多対多の関係のCREATETABLEでのMySQLエラー

主キー定義からNOTNULLを削除します-

CREATE TABLE resort_season(
  resortID MEDIUMINT UNSIGNED NOT NULL,
  seasonID MEDIUMINT UNSIGNED NOT NULL,
  FOREIGN KEY (resortID) REFERENCES resort (resortID),
  FOREIGN KEY (seasonID) REFERENCES season (seasonID),
  PRIMARY KEY (resortID, seasonID)
);