with t(dep_id, dep_nm, emp_nm) as (select 10, 'Administration', 'Clark Kent'
from dual union all select 110, 'Accounting', 'William Gietz'
from dual union all select 110, 'Accounting', 'Sheley Higgins'
from dual)
select n# as "Номер п/п"
     , case grouping_id(dep_id,emp_nm)
         when 0 then ''||dep_id
         when 1 then 'Количество сотрудников в отделе'
         else 'Общее количество сотрудников'
       end as "Идентификатор отдела"
     , dep_nm as "Название отдела"
     , case grouping_id(emp_nm)
         when 0 then emp_nm
         else ''||count(*)
       end as "Сотрудник"
  from (select row_number() over(order by dep_nm, emp_nm) n#, t.* from t)
 group by rollup((dep_id, dep_nm), (n#, emp_nm))
 order by dep_nm nulls last, n# nulls last
;