如何使用mysql为基于功能的登录系统设置访问级别？

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL,
    password VARCHAR(255) NOT NULL
);

CREATE TABLE roles (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL
);

CREATE TABLE permissions (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL
);

CREATE TABLE user_roles (
    user_id INT,
    role_id INT,
    PRIMARY KEY (user_id, role_id),
    FOREIGN KEY (user_id) REFERENCES users(id),
    FOREIGN KEY (role_id) REFERENCES roles(id)
);

CREATE TABLE role_permissions (
    role_id INT,
    permission_id INT,
    PRIMARY KEY (role_id, permission_id),
    FOREIGN KEY (role_id) REFERENCES roles(id),
    FOREIGN KEY (permission_id) REFERENCES permissions(id)
);

INSERT INTO users (username, password) VALUES ('admin', 'admin123');
INSERT INTO users (username, password) VALUES ('user1', 'user123');

INSERT INTO roles (name) VALUES ('admin');
INSERT INTO roles (name) VALUES ('user');

INSERT INTO permissions (name) VALUES ('create_post');
INSERT INTO permissions (name) VALUES ('edit_post');
INSERT INTO permissions (name) VALUES ('delete_post');

INSERT INTO user_roles (user_id, role_id) VALUES (1, 1); -- admin user
INSERT INTO user_roles (user_id, role_id) VALUES (2, 2); -- user1

INSERT INTO role_permissions (role_id, permission_id) VALUES (1, 1); -- admin can create post
INSERT INTO role_permissions (role_id, permission_id) VALUES (1, 2); -- admin can edit post
INSERT INTO role_permissions (role_id, permission_id) VALUES (1, 3); -- admin can delete post
INSERT INTO role_permissions (role_id, permission_id) VALUES (2, 1); -- user can create post

SELECT p.name AS permission
FROM users u
JOIN user_roles ur ON u.id = ur.user_id
JOIN role_permissions rp ON ur.role_id = rp.role_id
JOIN permissions p ON rp.permission_id = p.id
WHERE u.username = 'admin';