select dept_no, emp_no, max(salary) as salary from
(select d.dept_no as dept_no, d.emp_no as emp_no, s.salary as salary
from dept_emp d left join salaries s on d.emp_no = s.emp_no
where d.to_date = '9999-01-01'
and s.to_date = '9999-01-01' )
group by dept_no