Oracle递归查询简单示例
作者:michael-linux
最近在做一个树状编码管理系统,其中用到了oracle的树状递归查询,下面这篇文章主要给大家介绍了关于Oracle递归查询的相关资料,文中通过实例代码介绍的非常详细,需要的朋友可以参考下
1 数据准备
create table area_test( id number(10) not null, parent_id number(10), name varchar2(255) not null ); alter table area_test add (constraint district_pk primary key (id)); insert into area_test (ID, PARENT_ID, NAME) values (1, null, '中国'); insert into area_test (ID, PARENT_ID, NAME) values (11, 1, '河南省'); insert into area_test (ID, PARENT_ID, NAME) values (12, 1, '北京市'); insert into area_test (ID, PARENT_ID, NAME) values (111, 11, '郑州市'); insert into area_test (ID, PARENT_ID, NAME) values (112, 11, '平顶山市'); insert into area_test (ID, PARENT_ID, NAME) values (113, 11, '洛阳市'); insert into area_test (ID, PARENT_ID, NAME) values (114, 11, '新乡市'); insert into area_test (ID, PARENT_ID, NAME) values (115, 11, '南阳市'); insert into area_test (ID, PARENT_ID, NAME) values (121, 12, '朝阳区'); insert into area_test (ID, PARENT_ID, NAME) values (122, 12, '昌平区'); insert into area_test (ID, PARENT_ID, NAME) values (1111, 111, '二七区'); insert into area_test (ID, PARENT_ID, NAME) values (1112, 111, '中原区'); insert into area_test (ID, PARENT_ID, NAME) values (1113, 111, '新郑市'); insert into area_test (ID, PARENT_ID, NAME) values (1114, 111, '经开区'); insert into area_test (ID, PARENT_ID, NAME) values (1115, 111, '金水区'); insert into area_test (ID, PARENT_ID, NAME) values (1121, 112, '湛河区'); insert into area_test (ID, PARENT_ID, NAME) values (1122, 112, '舞钢市'); insert into area_test (ID, PARENT_ID, NAME) values (1123, 112, '宝丰市'); insert into area_test (ID, PARENT_ID, NAME) values (11221, 1122, '尚店镇');
2 start with connect by prior递归查询
2.1 查询所有子节点
select * from area_test start with name ='郑州市' connect by prior id=parent_id
2.2 查询所有父节点
select t.*,level from area_test t start with name ='郑州市' connect by prior t.parent_id=t.id order by level asc;
start with 子句:遍历起始条件,如果要查父结点,这里可以用子结点的列,反之亦然。
connect by 子句:连接条件。prior 跟父节点列parentid放在一起,就是往父结点方向遍历;prior 跟子结点列subid放在一起,则往叶子结点方向遍历。parent_id、id两列谁放在“=”前都无所谓,关键是prior跟谁在一起。
order by 子句:排序。
2.3 查询指定节点的,根节点
select d.*, connect_by_root(d.id) rootid, connect_by_root(d.name) rootname from area_test d where name='二七区' start with d.parent_id IS NULL connect by prior d.id=d.parent_id
2.4 查询巴中市下行政组织递归路径
select id, parent_id, name, sys_connect_by_path(name, '->') namepath, level from area_test start with name = '平顶山市' connect by prior id = parent_id
3 with递归查询
3.1 with递归子类
with tmp(id, parent_id, name) as ( select id, parent_id, name from area_test where name = '平顶山市' union all select d.id, d.parent_id, d.name from tmp, area_test d where tmp.id = d.parent_id ) select * from tmp;
3.2 递归父类
with tmp(id, parent_id, name) as ( select id, parent_id, name from area_test where name = '二七区' union all select d.id, d.parent_id, d.name from tmp, area_test d where tmp.parent_id = d.id ) select * from tmp;
补充:实例
我们称表中的数据存在父子关系,通过列与列来关联的,这样的数据结构为树结构。
现在有一个menu表,字段有id,pid,title三个。
查询菜单id为10的所有子菜单。
SELECT * FROM tb_menu m START WITH m.id=10 CONNECT BY m.pid=PRIOR m.id;
将PRIOR关键字放在m.id前面,意思就是查询pid是当前记录id的记录,如此顺延找到所有子节点。
查询菜单id为40的所有父菜单。
SELECT * FROM tb_menu m START WITH m.id=40 CONNECT BY PRIOR m.pid= m.id ORDER BY ID;
总结
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