Library Man Lite

USE library;
CREATE TABLE book (
    isbn VARCHAR(13) PRIMARY KEY,
    title VARCHAR(50),
    publisher VARCHAR(50),
    author VARCHAR(50),
    publish_date VARCHAR(50),
    cover_img VARCHAR(200),
    intro VARCHAR(200)
)

CREATE TABLE user(
    uid INTEGER PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(20) UNIQUE,
    gender CHAR,
    mail VARCHAR(20) UNIQUE,
    password VARCHAR(20)
);

CREATE TABLE real_Book(
    book_sn VARCHAR(20) PRIMARY KEY,
    isbn VARCHAR(13)
);

CREATE TABLE record(
    record_id INTEGER PRIMARY KEY AUTO_INCREMENT,
    customer_uid INTEGER DEFAULT -1,
    admin_uid INTEGER DEFAULT -1,
    book_sn VARCHAR(20) NOT NULL,
    operate_id INTEGER NOT NULL,
    ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);