create or replace directory files_one as 'C:/oracle18c/app/oracle/product/18.2.0/files_one';

  select  d.department_name, sum(e.salary)
  from employees e, departments d 
  where  d.DEPARTMENT_ID=e.DEPARTMENT_ID
  group by d.department_name; 

department_id department_name  
------------- ---------------- 
10            Administration   
20            Marketing        
30            Purchasing       
40            Human Resources  
50            Shipping
...
270           Payroll            

employee_id   last_name  salary departments_id
------------- ---------- ------ --------------
100           King       24000  90  
101           Kochhar    17000  90  
102           De Haan    17000  90  
103           Hunold     9000   60  
104           Ernst      6000   60 
...
206           William    8300   110