text: use employees_db;
  
  INSERT INTO
      department (name)
  VALUES
      ('Retail'),
      ('Engineering'),
  INSERT INTO
      role (title, salary, department_id)
  VALUES
      ('Cashier', 10000, 1),
      ('Maintenance', 20000, 1),
      ('Web Developer', 45000, 2),
  INSERT INTO
      employee (first_name, last_name, role_id, manager_id)
  VALUES
      ('Hank', 'Hill', 1, NULL),
      ('Ceri', 'Trammell', 3, NULL),
      ('Marty', 'McFly', 2, 1)