SELECT dept1
     , dept2
     , dept3
     , cnt1
     , cnt2
     , ROUND(cnt2 / cnt1, 2) cnt3
  FROM (SELECT ROWNUM rn
             , dept__cd
             , DECODE(dept_level, 1, dept__name) dept1
             , DECODE(dept_level, 2, dept__name) dept2
             , DECODE(dept_level, 3, dept__name) dept3
          FROM dept_table
         START WITH dept_level = 1
         CONNECT BY PRIOR dept__cd = dept_high_level
         ORDER SIBLINGS BY dept_order_by_no
        ) a
     , (SELECT u.dept__cd
             , COUNT(DISTINCT u.id) cnt1
             , COUNT(*) cnt2
          FROM user_table u
             , login_table l
         WHERE u.id = l.id
           AND l.login_date BETWEEN '2013-01-01' AND '2013-01-30'
         GROUP BY u.dept__cd
        ) b
 WHERE a.dept__cd = b.dept__cd(+)
 ORDER BY a.rn
;

마농님 넘 감사합니다 ^^

제 질문이 좀 모잘라 그렇지 쿼리가 많은 도움이 되었습니다 ~~~ 넘 감사드려요~