基础表创建：

with temp as (
select ‘公司‘ name, ‘1‘ id, ‘‘ pid from dual union all
select ‘部门1‘  name , ‘11‘ id, ‘1‘ pid from dual union all
select ‘部门2‘  name , ‘12‘ id, ‘1‘ pid from dual union all
select ‘员工11‘ name , ‘111‘ id , ‘11‘ pid from dual union all
select ‘员工12‘ name , ‘112‘ id , ‘11‘ pid from dual union all
select ‘员工21‘ name , ‘121‘ id , ‘12‘ pid from dual
)

等号左边的字段为基础，查询右边字段=左边字段的

从上往下查

通过根节点可以获取包括该根节点及以下的所有子节点

select * from temp
connect by prior  id= pid
start with id=‘1‘

根节点可以多选

select * from temp
connect by prior  id= pid
start with id in (‘11‘ ,‘12‘)

添加where语句

select * from temp
where id = ‘111‘
connect by prior  id= pid
start with id in (‘11‘ ,‘12‘)

从下往上查

select * from temp
connect by prior pid= id
start with id = ‘121‘

connect by prior id= pid start with id='1' 树结构查询

原文地址：https://www.cnblogs.com/-beauTiFul/p/9121553.html