oracle ：
查找所有下级
　　select * from tbl_test start with id=1 connect by prior id=pid
查找所有上级
select * from tbl_test start with id=5 connect by prior pid=id

sql server：

sql server 递归获取下级和当前级
with cte as
(
select OrgCode,OrgParentCode, 0 as lvl from SysOrgan
where OrgCode = ‘zfj‘
union all
select d.OrgCode,d.OrgParentCode,lvl + 1 from cte c inner join SysOrgan d
on c.OrgCode = d.OrgParentCode
)
select * from cte

Oracle获取下级节点