含下級:select a.id from 表 a start with a.id='123'connect by prior a.id=a.parentid
含上級:select a.id from 表 a start with a.id='123' connect by prior a.parentid=a.id
含下一級:select a.id from 表 a start with a.parentid='123' connect by prior a.parentid=a.id
含下級:select a.id from 表 a start with a.id='123'connect by prior a.id=a.parentid
含上級:select a.id from 表 a start with a.id='123' connect by prior a.parentid=a.id
含下一級:select a.id from 表 a start with a.parentid='123' connect by prior a.parentid=a.id