text: DROP TABLE IF EXISTS department;
  
  CREATE TABLE department (
      id INT AUTO_INCREMENT PRIMARY KEY,
      name VARCHAR(30) NOT NULL
  );
  
  CREATE TABLE role (
    id INT AUTO_INCREMENT PRIMARY KEY,
    title VARCHAR(30) NOT NULL,
    salary DECIMAL NOT NULL,
    department_id INT NOT NULL,
    CONSTRAINT fk_department FOREIGN KEY (department_id) REFERENCES department(id) ON DELETE CASCADE
  );
  
  CREATE TABLE employee (
      id INT AUTO_INCREMENT,
      first_name VARCHAR(30),
      last_name VARCHAR(30),
      role_id INT(10),
      manager_id INT(10),
      PRIMARY KEY (id)
  );