-- https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/SELECT.html
SELECT d.department_id as d_dept_id, e.department_id as e_dept_id,
      e.last_name
   FROM departments d FULL OUTER JOIN employees e
   ON d.department_id = e.department_id
   ORDER BY d.department_id, e.last_name;