derby 自增主键

CREATE TABLE MAPS

   (
      MAP_ID INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
      MAP_NAME VARCHAR(24) NOT NULL,
      REGION VARCHAR(26),
      AREA DECIMAL(8,4) NOT NULL,
      PHOTO_FORMAT VARCHAR(26) NOT NULL,
      PICTURE BLOB(102400),
      UNIQUE (MAP_ID, MAP_NAME)
   );