根据根节点得到所有的叶子节点 CONNECT BY

SELECT *  FROM (SELECT t2.*, LEAD(LEVELS) OVER(ORDER BY RN) aa,                CASE                  WHEN LEAD(LEVELS) OVER(ORDER BY RN) > LEVELS THEN                   0                  ELSE                   1                END LEAF           FROM (SELECT ROWNUM rn, t.*, LEVEL LEVELS                    FROM test t                   START WITH n_parent_id = 0                  CONNECT BY PRIOR n_id = n_parent_id) t2)WHERE leaf = 1