如何使用Oracle CONNECT BY将层次结构中的所有值链接到某个值

Question

关系模型是

1   3   
 \ / \
  2   4
   \
    7   5     8
     \ /     /
      6     9

表是:

select 2 child, 1 father from dual
union all
select 2 child, 3 father from dual
union all
select 4 child, 3 father from dual
union all
select 7 child, 2 father from dual
union all
select 6 child, 5 father from dual
union all
select 6 child, 7 father from dual
union all
select 9 child, 8 father from dual

如何将所有值与值CHILD或FATHER = 2相关联？

肯定是

1,2,3,4,5,6,7

并不是

8,9

因为它与价值2无关.

如何通过使用CONNECT BY语句来实现这一点？谢谢.

ps这个解决方案离我很近但不适用于我的模型:

使用oracle connect by查找邻接列表模型中的所有节点

数据库版本 - 10.2.0.5.0

模型与甲骨文 - 连接 - 通过

所以,大概的策略可能是这样的(例如从node = 7开始):

第1步(方向=向上)

select t1.father,connect_by_root father as root,connect_by_isleaf from 
(my_table) t1
start with father=7
connect by prior father = child 

结果是7,2,1,3,其中1,3是高级根(isleaf = 1)

第2步(获取1,3方向的路线=向下)

select t1.child,connect_by_root father as root,connect_by_isleaf from 
(my_table) t1
start with father=1
connect by father = prior child 

结果是2,7,6,其中6是低级根(isleaf = 1)

select t1.child,connect_by_root father as root,connect_by_isleaf from 
(my_table) t1
start with father=3
connect by father = prior child

结果是2,7,6,4其中6,4是低级根(isleaf = 1)

第3步(获得6,4方向的路线=向上)

select t1.father,connect_by_root father as root,connect_by_isleaf from 
(my_table) t1
start with child=6
connect by prior father = child 

结果是5,7,2,1,3其中5,1,3是高级别根(isleaf = 1)这个结果我发现node = 5

然后我必须改变方向向下..然后再次向上..然后再次下降..

但如何在一个选择中结合所有这些步骤？对于初学者来说很难.请帮帮我.

Answer 1

对于您的输出，您不需要定向图表，因此将反向链接添加到所有现有链接。这就是我在子查询“bi”中所做的。然后您使用 nocyle 通过查询连接。

    with h as (
                     SELECT 2 child, 1 father FROM dual
                     UNION ALL
                     SELECT 2 child, 3 father FROM dual
                     UNION ALL
                     SELECT 4 child, 3 father FROM dual
                     UNION ALL
                     SELECT 7 child, 2 father FROM dual
                     UNION ALL
                     SELECT 6 child, 5 father FROM dual
                     UNION ALL
                     SELECT 6 child, 7 father FROM dual
                     UNION ALL
                     SELECT 9 child, 8 father FROM dual
            ),
    bi as (select * from h union all select father , child from h )     
    select distinct father from bi
    start with child = 2
    connect by nocycle
    prior father = child

我在查询中使用“with”表示法以获得更好的可读性。