Ошибка в коде базы данных ПАМАГИТЕ СТУДЕНТУ

20:11:34 CREATE TABLE IF NOT EXISTS `Сайт`.`Сайт` ( `user_id` INT NOT NULL, `admin_id` INT NOT NULL, `book_id` INT NOT NULL, `comments_id` INT NOT NULL, PRIMARY KEY (`user_id`, `admin_id`, `book_id`), INDEX `книги_idx` (`book_id` ASC), INDEX `админ_idx` (`admin_id` ASC), INDEX `комментарии_idx` (`comments_id` ASC), CONSTRAINT `пользователь` FOREIGN KEY (`user_id`) REFERENCES `Сайт`.`пользователь` (`id_user`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `комментарии` FOREIGN KEY (`comments_id`) REFERENCES `Сайт`.`комментарии` (`comment_id`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `книги` FOREIGN KEY (`book_id`) REFERENCES `Сайт`.`книги` (`id_book`) ON DELETE NO ACTION ON UPDATE CASCADE, CONSTRAINT `админ` FOREIGN KEY (`admin_id`) REFERENCES `Сайт`.`админ` (`id_admin`) ON DELETE CASCADE ON UPDATE CASCADE) ENGINE = InnoDB Error Code: 1215. Cannot add foreign key constraint 0.015 sec