text: -- select all employees
  select e.id, e.first_name, e.last_name
  , r.title, r.salary, d.name as department
  , concat(m.first_name,' ',m.last_name) as manager, rm.title as manger_title
  from employee e
  left join role r on e.role_id=r.id
  left join department d on d.id=r.department_id
  left join employee m on e.manager_id=m.id
  left join role rm on m.role_id=rm.id
  ;
  
  -- select employees by department
  select e.id, e.first_name, e.last_name
  , r.title, r.salary, d.name as department
  , concat(m.first_name,' ',m.last_name) as manager, rm.title as manger_title
  from employee e
  left join role r on e.role_id=r.id
  left join department d on d.id=r.department_id
  left join employee m on e.manager_id=m.id
  left join role rm on m.role_id=rm.id
  order by r.department_id
  ;
  
  -- select employees by manager name
  select e.id, e.first_name, e.last_name
  , r.title, r.salary, d.name as department
  , concat(m.first_name,' ',m.last_name) as manager, rm.title as manger_title
  from employee e
  left join role r on e.role_id=r.id
  left join department d on d.id=r.department_id
  left join employee m on e.manager_id=m.id
  left join role rm on m.role_id=rm.id
  order by concat(m.first_name,' ',m.last_name)
  ;
  