with t as
( select '컴퓨터' cate_name, 1 cate_level from dual union all
 select '노트북', 2 from dual union all
 select '넷북',  2 from dual union all
 select '삼성',  3 from dual union all
 select '핸드폰', 1 from dual union all
 select '아이폰', 2 from dual
)
select cate_name
   , cate_level
   , lpad(' ', (cate_level-1)*10, ' ')||cate_name
from t m
; 

SELECT *
  FROM t
 START WITH cate_level = 1
 CONNECT BY PRIOR cate_cd = DECODE(cate_level, 3, cate3_cd, cate2_cd)
 ORDER SIBLINGS BY cate_order
;