WITH t AS
(
SELECT 1 id, 'A01' cd, 'A01' pcd, '' ocd, '20130101' dt, 'A' item, '' yn　FROM dual
UNION ALL SELECT 1, 'B01', 'B01', 'A01', '20130501', 'B', ''　FROM dual
UNION ALL SELECT 1, 'B02', 'B01', ''   , '20131101', 'B', ''　FROM dual
UNION ALL SELECT 1, 'B03', 'B01', ''   , '20140101', 'B', ''　FROM dual
UNION ALL SELECT 1, 'C01', 'C01', 'B03', '20140301', 'C', 'Y' FROM dual
UNION ALL SELECT 1, 'D01', 'D01', ''   , '20130205', 'D', ''　FROM dual
UNION ALL SELECT 1, 'E01', 'E01', 'D01', '20130501', 'E', ''　FROM dual
UNION ALL SELECT 1, 'F01', 'F01', 'E01', '20140301', 'F', 'Y' FROM dual
UNION ALL SELECT 2, 'D02', 'D02', ''   , '20130201', 'D', ''　FROM dual
UNION ALL SELECT 2, 'E02', 'E02', 'D02', '20130501', 'E', ''　FROM dual
UNION ALL SELECT 2, 'F02', 'F02', 'E02', '20140301', 'F', 'Y' FROM dual
)
SELECT id, cd
     , CONNECT_BY_ROOT(dt) dt
  FROM t
 WHERE yn = 'Y'
 START WITH cd = pcd AND ocd IS NULL
 CONNECT BY NOCYCLE PRIOR cd = NVL(ocd, pcd)
;