컬럼은
DEPT_CD / DEPT_NM / DEPT_LVL / HGRNK_DEPT_CD / DEPT_RNKG_1 / DEPT_RNKG_2 / DEPT_RNKG_3
0000                   전사                   0                               -1                          1                                 0                           0
1000                    본사                 1                                 0000                  1                                  0                           0
6000                    현업                  1                                0000                     1                               0                           0
1040                 임원실                4                                  1000                 1                                    0                          0

전사-
  본사
    임원실(하위 없음)
    다른거1(하위 있음)
    다른거2(하위 있음)
  현업(하위있음)
    다른거1(하위 있음)
    다른거2(하위 있음)


형식으로 되어있는데요 ..
제가 짠 쿼리는

SELECT LEVEL dept_lvl, dept_cd, dept_nm, hgrnk_dept_cd
FROM hrha_dept_cd
CONNECT BY PRIOR dept_cd = hgrnk_dept_cd
START WITH dept_cd = '0000';

Loop detected during CONNECT BY operation이라고 뜨는데
START WITH dept_cd = '6000'; 을 주면 잘 나오는데
 

START WITH dept_cd = '1000'; 이나 루트 0000을 주면 안나옵니다
 

에러가 발생하는데 휴.. 자료도 없고 ㅠㅠ 도와주세요