   isbn_10       		VARCHAR(20)     NOT NULL,
   CONSTRAINT author_book_pk
     PRIMARY KEY (author_id, isbn_10)
-);+);

    PRIMARY KEY (isbn_10)
);

CREATE TABLE user_book
(
  user_id			INT         	NOT NULL,
  isbn_10       	VARCHAR(20)     NOT NULL,
  entry_date        DATE        	NOT NULL,
  delete_date		DATE,

CREATE TABLE author
(
  author_id				INT         	NOT NULL	AUTO_INCREMENT,
  author_name		VARCHAR(255)     NOT NULL,
  CONSTRAINT author_id_pk
    PRIMARY KEY (author_id)
);
