mysql添加表关系

CREATE TABLE users (
    user_id INT PRIMARY KEY,
    username VARCHAR(50)
);

CREATE TABLE user_id_cards (
    id_card_id INT PRIMARY KEY,
    user_id INT,
    FOREIGN KEY (user_id) REFERENCES users(user_id)
);

CREATE TABLE departments (
    department_id INT PRIMARY KEY,
    department_name VARCHAR(50)
);

CREATE TABLE employees (
    employee_id INT PRIMARY KEY,
    department_id INT,
    employee_name VARCHAR(50),
    FOREIGN KEY (department_id) REFERENCES departments(department_id)
);

CREATE TABLE students (
    student_id INT PRIMARY KEY,
    student_name VARCHAR(50)
);

CREATE TABLE courses (
    course_id INT PRIMARY KEY,
    course_name VARCHAR(50)
);

CREATE TABLE student_courses (
    student_id INT,
    course_id INT,
    PRIMARY KEY (student_id, course_id),
    FOREIGN KEY (student_id) REFERENCES students(student_id),
    FOREIGN KEY (course_id) REFERENCES courses(course_id)
);

SET FOREIGN_KEY_CHECKS=0;
-- 执行插入操作
SET FOREIGN_KEY_CHECKS=1;