سؤال فى Set Operators هل ليس له حل

2. The HR department needs a list of countries that have no departments located in them. Display the country ID and the name of the countries. Use set operators to create this report.




هل له حل عندكم أنا جربت ووصلت لبدايات وهى

column to_number(null) loc_id_dum noprint
select to_number(null) loc_id_dum,country_id,country_name
from countries

where (to_nuber(null) loc_id_dum,country_id) in
                    (select location_id,to_char(null)cou_id_dum,
                              to_char(null) cou_nm_dum
                                        from locations
                                         MINUS
                                         select location_id
                                           from departments)