CREATE TABLE classes (
id INT UNSIGNED NOT NULL AUTO_INCREMENT,
name VARCHAR(30) NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB CHARSET=utf8;
接下来,大家在students表中添加一个class_id字段作为外键:
CREATE TABLE students (
id INT UNSIGNED NOT NULL AUTO_INCREMENT,
name VARCHAR(30) NOT NULL,
class_id INT UNSIGNED,
PRIMARY KEY (id),
CONSTRAINT fk_class_id FOREIGN KEY (class_id) REFERENCES classes(id)
) ENGINE=InnoDB CHARSET=utf8;