text: -- View all employees
  -- SELECT 
  -- e.id AS id,
  -- e.first_name AS first_name,
  -- e.last_name AS last_name,
  -- roles.title AS title,
  -- departments.name AS department,
  -- roles.salary AS salary,
  -- CONCAT(manager.first_name, ' ', manager.last_name) AS manager
  -- FROM employees e
  -- LEFT JOIN roles
  -- ON roles.id = e.role_id
  -- LEFT JOIN departments
  -- ON departments.id = roles.department_id
  -- LEFT JOIN employees manager
  -- ON e.id = manager.manager_id;
  
  -- View all roles
  SELECT 
  roles.id AS id,
  roles.title AS title,
  departments.name AS department,
  roles.salary AS salary
  FROM roles
  JOIN departments
  ON roles.department_id = departments.id;
  
  -- View all departments
  SELECT * FROM departments;
  
  SELECT 
  employees.first_name, 
  employees.last_name, 
  roles.title, 
  roles.salary, 
  departments.name, 
  CONCAT(e.first_name, ' ' ,e.last_name) AS Manager 
  FROM employees 
  INNER JOIN roles 
  on roles.id = employees.role_id 
  INNER JOIN departments 
  on departments.id = roles.department_id 
  left join employees e 
  on employees.manager_id = e.id;