通过数据库编程进行递归（Oracle）

一、用于测试数据及其结构和生成该测试数据的sql语句如下：
1、测试数据
nodeId     parentId
---------- ----------
A01        A
A02        A
A03        A
A0101      A01
A0102      A01
A0201      A02
A0202      A02
B01        B
B02        B
B0201      B02
B0202      B02
B020101    B0201
B020102    B0201

2、建表及生成数据的sql语句
create table tree
(
    nodeId varchar2(10) not null,
    parentId varchar2(10) not null
);

insert into tree
select 'A01', 'A' from dual union all
select 'A02', 'A' from dual union all
select 'A03', 'A' from dual union all
select 'A0101', 'A01' from dual union all
select 'A0102', 'A01' from dual union all
select 'A0201', 'A02' from dual union all
select 'A0202', 'A02' from dual union all
select 'B01', 'B' from dual union all
select 'B02', 'B' from dual union all
select 'B0201', 'B02' from dual union all
select 'B0202', 'B02' from dual union all
select 'B020101', 'B0201' from dual union all
select 'B020102', 'B0201' from dual;

二、递归
1、递归sql
select parentId, nodeId
from tree
start with parentId = 'B02'
connect by parentId = prior nodeId
order by parentId, nodeId;

2、执行结果
parentId   nodeId
B02 B0201
B02 B0202
B0201 B020101
B0201 B020102

指定parentId时要注意，oracle是区分大小写的。