Oracle 递归查询为目录树指定层级关系

• 正向递归（根节点向叶子节点找）

select o.organ_id,o.organ_name,level  from organ o 
start with o.organ_id='1' 
 connect by prior  o.parent_id =o.organ_id
 order by level

• 反向递归（叶子节点向根节点找）

 select organ_id,organ_name,level  from organ 
 start with organ_id='42' 
 connect by nocycle prior  parent_id =organ_id
  order by level desc