Oralce之递归算法
Oracle递归算法的经典用途，比如 多级部门下，子部门不能作为父部门的父部门。
Oracle递归算法的经典用途，比如 多级部门下，，子部门不能作为父部门的父部门。
有点拗口，比方说吧，爸爸部门下有甲儿子部门和乙儿子部门，甲或乙儿子部门不能成为爸爸部门的上级部门。
这个是很多管理系统的多级分类下的经典需求。
好吧。给出部门表结构--Department。
判断子部门是否能成为爸爸部门的上级部门，采用到了递归。SQL:
其中 CONNECT BY PRIOR .... START WITH..... 就是递归。 #deptNo# 、#parentNo# 分别代表 子部门 和 爸爸部门。
如果返回值等于1，则子部门不能成为爸爸部门的上级部门；如果返回值不等于1，反之。
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