mysql数据库枚举类型

ENUM('value1', 'value2', ..., 'valueN')

CREATE TABLE schedule (
    id INT AUTO_INCREMENT PRIMARY KEY,
    day ENUM('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday')
);

INSERT INTO schedule (day) VALUES ('Monday'); -- 合法
INSERT INTO schedule (day) VALUES ('Funday'); -- 非法，会报错

ALTER TABLE schedule MODIFY COLUMN day ENUM('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday', 'Funday');

CREATE TABLE days (
    id TINYINT PRIMARY KEY,
    name VARCHAR(20) NOT NULL UNIQUE
);

CREATE TABLE schedule (
    id INT AUTO_INCREMENT PRIMARY KEY,
    day_id TINYINT,
    FOREIGN KEY (day_id) REFERENCES days(id)
);