select d.department_name, t.avg_salary
from departments d,
(select e.department_id,avg(salary) avg_salary
from employees e
group by department_id) t
where d.department_id=t.department_id
order by t.avg_salary
select d.department_name, t.avg_salary
from departments d,
(select e.department_id,avg(salary) avg_salary
from employees e
group by department_id) t
where d.department_id=t.department_id
order by t.avg_salary