 (
   user_id			INT         	NOT NULL,
   isbn       	VARCHAR(13)     NOT NULL,
-  entry_date        DATE        	NOT NULL,
-  delete_date		DATE,
   CONSTRAINT user_book_pk
     PRIMARY KEY (user_id, isbn)
 );

  title         	VARCHAR(100)	NOT NULL,
  author        VARCHAR(255) NOT NULL,
  publishers		VARCHAR(100)	NOT NULL,
  publish_date		DATE			NOT NULL,
  thumbnail_url		VARCHAR(255),			
  CONSTRAINT isbn_pk 
    PRIMARY KEY (isbn)

(
  user_id			INT         	      NOT NULL,
  isbn       	VARCHAR(13)     NOT NULL,
  CONSTRAINT user_book_pk
    PRIMARY KEY (user_id, isbn)
);
