text: DROP DATABASE IF EXISTS staffing_db;
  CREATE DATABASE staffing_db;
  
  USE staffing_db;
  
  CREATE TABLE department (
    id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(30)
  );
  
  CREATE TABLE role (
      id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
      title VARCHAR(30),
      salary DECIMAL,
      department_id INT NOT NULL,
      FOREIGN KEY (department_id)
      REFERENCES department (id)
  );
  
  CREATE TABLE employee (
      id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
      first_name VARCHAR(30),
      last_name VARCHAR(30),
      role_id INT NOT NULL,
      manager_id INT,
      FOREIGN KEY (role_id)
      REFERENCES role (id),
      FOREIGN KEY (manager_id)
      REFERENCES employee(id)
  );