Oracle通过递归查询父子兄弟节点方法示例

 // 查询id为101的所有后代节点，包含101在内的各级父节点
 select t.* from SYS_ORG t start with id = '101' connect by parent_id = prior id

select t.*
 from SYS_ORG t
 where not exists (select 1 from SYS_ORG s where s.parent_id = t.id)
 start with id = '101'
connect by parent_id = prior id

 select t.*
 from SYS_ORG t
 start with id = '401000501'
 connect by prior parent_id = id

 select * from SYS_ORG t
 where exists (select * from SYS_ORG s where t.parent_id=s.parent_id and s.id='401000501')

with tmp as(
  select t.*, level leaf  
  from SYS_ORG t    
  start with t.parent_id = '0'  
  connect by t.parent_id = prior t.id)
select *        
  from tmp        
where leaf = (select leaf from tmp where id = '401000501');

with tmp as(
 select t.*, level lev
 from SYS_ORG t
 start with t.parent_id = '0'
 connect by t.parent_id = prior t.id) 
select b.*
from tmp b,(select *
   from tmp
   where id = '401000501' and lev = '2') a
where b.lev = '1'
union all
select *
from tmp
where parent_id = (select distinct x.id
    from tmp x, --祖父
      tmp y, --父亲
      (select *
      from tmp
      where id = '401000501' and lev > '2') z --儿子
    where y.id = z.parent_id and x.id = y.parent_id);