declare
  rg_name  VARCHAR2(40) := 'CITY_NAME';
  rg_id    RecordGroup;
	gc_id    GroupColumn;
	errcode number;

 q1 varchar2(650) := 'SELECT '' ''||CITY_NAME CITY_NAME, CITY_ID FROM CITIES  WHERE CITIES.CITY_ID = :block2.CITY_ID AND COUNTRY_ID = :block2.COUNTRY_ID';
 begin
  :system.message_level := 5;
	rg_id := Find_Group(rg_name);
	if not Id_Null(rg_id) then
	   Delete_Group(rg_id);
	ELSE IF
		Id_Null(rg_id) then
rg_id := Create_Group(rg_name);
                                          
gc_id := Add_Group_Column(rg_id, 'CITY_NAME',CHAR_COLUMN,40);
gc_id := Add_Group_Column(rg_id, 'CITY_ID', char_COLUMN,5);
	end if;

	errcode := Populate_Group_with_query(rg_id,q1);
	populate_list('CITY_NAME',rg_id);
	end if;

execute_query;
END;