oracle 树形查询函数,oracle 递归查询一个树形结构的菜单
关键字：oracle connect by level 树状结构表
定义如下id 和 名称描述
1—
省长
2—
市长
3—
县长
4— 镇长
5— 村长
其他(6-15)— 平民(没有管辖任何人)
只有
省长、市长和
县长能处理问题，那么每个人出了问题应该
首先找谁来解决？
省长权利最大，自己出了问题自己解决，别人也没法知道; 可以认为在关系表里省长的父节点是自己。
Db代码
create table person(id int primary key, description varchar2(50));
create table relationship(child int, parent int, primary key(child,parent));
insert into person values(1,‘省长’);
insert into person values(2,‘市长’);
insert into person values(3,‘县长’);
insert into person values(4,‘镇长’);
insert into person values(5,‘村长’);
insert into person values(6,‘平民’);
...//省略的都是平民
insert into person values(15,‘平民’);
insert into relationship values(1,1); //关系如下
insert into relationship values(2,1);
insert into relationship values(3,1);
insert into relationship values(5,2);
insert into relationship values(6,2);
insert into relationship values(4,3);
insert into relationship values(7,3);
insert into relationship values(8,3);
insert into relationship values(9,3);
insert into relationship values(10,4);
insert into relationship values(11,4);
insert into relationship values(12,4);
insert into relationship values(13,4);
insert into relationship values(14,5);
insert into relationship values(15,5);
create table person(id int primary key, description varchar2(50));
create table relationship(child int, parent int, primary key(child,parent));
insert into person values(1,‘省长’);
insert into person values(2,‘市长’);
insert into person values(3,‘县长’);
insert into person values(4,‘镇长’);
insert into person values(5,‘村长’);
insert into person values(6,‘平民’);
...//省略的都是平民
insert into person values(15,‘平民’);
insert into relationship values(1,1); //关系如下
insert into relationship values(2,1);
insert into relationship values(3,1);
insert into relationship values(5,2);
insert into relationship values(6,2);
insert into relationship values(4,3);
insert into relationship values(7,3);
insert into relationship values(8,3);
insert into relationship values(9,3);
insert into relationship values(10,4);
insert into relationship values(11,4);
insert into relationship values(12,4);
insert into relationship values(13,4);
insert into relationship values(14,5);
insert into relationship values(15,5);
查看一下关系树：
Oracle代码
select rpad('---',(level-1)*3,'---')||child relation_tree
from relationship
start with child=parent
connect by nocycle prior child=parent; --结果如下
RELATION_TREE
------------------
1
---2
------5
---------14
---------15
------6
---3
------4
---------10
---------11
---------12
---------13
------7
------8
------9
已选择15行。
select rpad('---',(level-1)*3,'---')||child relation_tree
from relationship
start with child=parent
connect by nocycle prior child=parent; --结果如下
RELATION_TREE
------------------
1
---2
------5
---------14
---------15
------6
---3
------4
---------10
---------11
---------12
---------13
------7
------8
------9
已选择15行。
查看父子关系情况：
Oracle代码
select child,parent
from relationship
start with child=parent
connect by nocycle prior child=parent
order by parent; --结果如下
CHILD PARENT
---------- ----------
11
21
31
52
62
43
83
73
93
114
124
104
134
145
155
已选择15行。
select child,parent
from relationship
start with child=parent
connect by nocycle prior child=parent
order by parent; --结果如下
CHILD PARENT
---------- ----------
1 1
2 1
3 1
5 2
6 2
4 3
8 3
7 3
9 3
11 4
12 4
10 4
13 4
14 5
15 5
已选择15行。
下面要看一看：每个人有事时，首先找到谁来处理？不能每个人有事都找省长吧。
下面的sql使用了oracle家的两个变态函数：first_value & connect_by_root
Oracle代码
select distinct child ,first_value(parent)over(partition by child order by lv) parent
from(
select connect_by_root(r.child) child, p.description descr, level lv, r.parent
from person p ,relationship r
where p.id= r.parent
connect by nocycle prior r.parent=r.child
)
where descr in('省长','市长','县长')
order by parent,child; --结果如下
CHILD PARENT
---------- ----------
11
21
31
52
62
142
152
43
73
83
93
103
113
123
133
已选择15行。
select distinct child ,first_value(parent)over(partition by child order by lv) parent
from(
select connect_by_root(r.child) child, p.description descr, level lv, r.parent
from person p ,relationship r
where p.id= r.parent
connect by nocycle prior r.parent=r.child
)
where descr in('省长', '市长', '县长')
order by parent,child; --结果如下
CHILD PARENT
---------- ----------
1 1
2 1
3 1
5 2
6 2
14 2
15 2
4 3
7 3
8 3
9 3
10 3
11 3
12 3
13 3
已选择15行。
这个sql到底行不行，再加条数据看看
Db代码
insert into person values(333,‘县长’);
insert into person values(555,‘村长’);
insert into person values(666,‘平民’);
insert into person values(777,‘平民’);
insert into relationship values(333,1);
insert into relationship values(555,333);
insert into relationship values(666,555);
insert into relationship values(777,666);
--666这个平民有￥，777愿意跟着他(这条记录比较特殊)