select…start with…connect by…prior
1.查找一个节点的所有直属子节点（节点本身+所有后代），有以下两种写法。
select id, typename, typecode, parentid, ordernum from purchase_type where status = 1 start with id = ‘15‘ connect by parentid = prior id
order siblings by ordernum
或
select id, typename, typecode, parentid, ordernum from purchase_type where status = 1 start with id = ‘15‘ connect by prior id = parentid order siblings by ordernum
显示结果：
2.查找一个节点的所有直属父节点（节点本身+所有祖宗（父类的父类....））。
select id, typename, typecode, parentid, ordernum
from purchase_type
where status = 1
start with id = ‘136‘
connect by id = prior parentid
order siblings by ordernum
或
select id, typename, typecode, parentid, ordernum from purchase_type where status = 1 start with id = ‘136‘ connect by prior parentid = id order siblings by ordernum
显示结果：
原文：http://www.cnblogs.com/chengx/p/5910227.html