oracle的level虚列的使用

oracle的level虚列的使用

SELECT 0 id, '' org_no, '' org_name
FROM dual
UNION
SELECT 1 id,
       a.org_no || ',' || a.org_type org_no,
       lpad('　', 4 * (LEVEL - 1)) || a.org_name org_name
FROM o_org a
WHERE LEVEL <= 4
START WITH a.org_no = '35406'
CONNECT BY a.p_org_no = PRIOR a.org_no