创建表和主外键

CREATE TABLE SC_DISTRICT
(
  ID         NUMBER(10)                  NOT NULL,
  PARENT_ID  NUMBER(10),
  NAME       VARCHAR2(255 BYTE)          NOT NULL
);

ALTER TABLE SC_DISTRICT ADD (
  CONSTRAINT SC_DISTRICT_PK
 PRIMARY KEY
 (ID));

ALTER TABLE SC_DISTRICT ADD (
  CONSTRAINT SC_DISTRICT_R01 
 FOREIGN KEY (PARENT_ID) 
 REFERENCES SC_DISTRICT (ID)
);

插入数据

insert into A_DISTRICT (id, parent_id, name) values (1, null, '河南省');
insert into A_DISTRICT (id, parent_id, name) values (2, null, '山东省');
insert into A_DISTRICT (id, parent_id, name) values (3, 1, '郑州市');
insert into A_DISTRICT (id, parent_id, name) values (4, 1, '开封市');
insert into A_DISTRICT (id, parent_id, name) values (5, 1, '商丘市');
insert into A_DISTRICT (id, parent_id, name) values (6, 3, '中原区');
insert into A_DISTRICT (id, parent_id, name) values (7, 3, '金水区');
insert into A_DISTRICT (id, parent_id, name) values (8, 3, '二七区');
insert into A_DISTRICT (id, parent_id, name) values (9, 3, '城管回族区');
insert into A_DISTRICT (id, parent_id, name) values (10, 3, '上街区');
insert into A_DISTRICT (id, parent_id, name) values (11, 3, '惠济区');
insert into A_DISTRICT (id, parent_id, name) values (12, 4, '开封县');
insert into A_DISTRICT (id, parent_id, name) values (13, 4, '杞县');
insert into A_DISTRICT (id, parent_id, name) values (14, 4, '兰考县');
insert into A_DISTRICT (id, parent_id, name) values (15, 4, '通许县');
insert into A_DISTRICT (id, parent_id, name) values (16, 13, '城关镇');
insert into A_DISTRICT (id, parent_id, name) values (17, 13, '五里河镇');
insert into A_DISTRICT (id, parent_id, name) values (18, 13, '邢口镇');
insert into A_DISTRICT (id, parent_id, name) values (19, 13, '柿园乡');
insert into A_DISTRICT (id, parent_id, name) values (20, 13, '城郊乡');

递归语法和主要使用函数

      select * from 表 start with 条件入口 connect by prior id =  parent_id（向下）

      select * from 表 start with 条件入口 connect by prior parent_id = id（向上）

如果不写prior，表明前序遍历 未指明遍历方向，所以不进行递归，习惯上会在语句后面加上order by排序和group by分组

      connect_by_root(列名)  查询根节点

      connect_by_isleaf   查询是否叶子节点，0是，1不是

      sys_connect_by_path  查询递归路径

实战

查询根节点

select id, parent_id, name from a_district start with parent_id is null connect by id = parent_id order by id

递归查询 杞县 的所有上级节点（包含当前节点）

select id, parent_id, name from a_district start with name='杞县' connect by prior parent_id = id order by id

递归查询 杞县 的所有上级节点（包含当前节点和根节点）

select id, parent_id, name,connect_by_root(id) city_id, connect_by_root(name) city_name from a_district 
       start with name='杞县' connect by prior parent_id = id order by id

递归查询 杞县 的所有子城镇乡（包含当前节点）

select id, parent_id, name from a_district start with name='杞县' connect by prior id = parent_id order by id

递归查询 开封市 的所有城镇乡（包含当前节点和根节点）

select id, parent_id, name, connect_by_root(id) city_id, connect_by_root(name) city_name from a_district 
       start with  name='开封市' connect by prior id = parent_id order by id

上行递归查询 城郊乡 深度、是否包含叶子节点

select id, name, parent_id, level, connect_by_isleaf isleaf from a_district start with name = '城郊乡' connect by prior parent_id = id order by id

下行递归查询 河南省 深度、是否包含叶子节点

select id, name, parent_id, level, connect_by_isleaf isleaf from a_district start with name = '河南省' connect by prior id = parent_id order by id

上行递归查询 杞县 路径

select id, name, parent_id, substr(sys_connect_by_path(name,'->'),3) name_path from a_district 
       start with name='杞县' connect by prior parent_id = id order by id

下行递归查询 河南省 路径

select id, name, parent_id, substr(sys_connect_by_path(name,'->'),3) name_path from a_district 
       start with name='河南省' connect by prior id = parent_id order by id

综合使用

select id, name, parent_id, level, connect_by_isleaf isleaf, substr(sys_connect_by_path(name,'->'),3) name_path from a_district
        start with name='河南省' connect by prior id = parent_id order by id

Oracle递归查询