select de.emp_no,dm.emp_no as manager_no from dept_manager as dm innerjoin dept_emp as de on dm.dept_no = de.dept_no where dm.to_date = '9999-01-01' and de.to_date = '9999-01-01' and de.emp_no <> dm.emp_no
select de.emp_no,dm.emp_no as manager_no from dept_manager as dm,dept_emp as de where dm.dept_no = de.dept_no and dm.to_date = '9999-01-01' and de.to_date = '9999-01-01' and de.emp_no <> dm.emp_no