甲骨文树：遗漏的前身和追随者

Question

我想获得递归查询的帮助。 对我来说，“按优先顺序连接”是新手，我在使用它时遇到了一些困难。

我正在寻找一种方法来获取按连通性（父子关系）分类的数据列表，同时省略Oracle 11gR2中的某些类型的记录。 换句话说，我有一个像树的结构，我想要一棵新的树，其中一些无效数据将被忽略。

例如，这是我表中拥有的信息，我称之为“ OriginalSequence”

WITH OriginalSequence AS
(
SELECT 'ID1' AS KEY, 'INVALID1' AS CHILD, NULL AS PARENT FROM dual union ALL
SELECT 'INVALID1'  , 'ID2'              , 'ID1'          FROM dual union ALL
SELECT 'INVALID1'  , 'ID3'              , 'ID1'          FROM dual union ALL
SELECT 'ID2'       , 'INVALID2'         , 'INVALID1'     FROM dual union ALL
SELECT 'ID3'       , 'ID4'              , 'INVALID1'     FROM dual union ALL
SELECT 'ID3'       , 'INVALID3'         , 'INVALID1'     FROM dual union ALL
SELECT 'INVALID2'  , NULL               , 'ID2'          FROM dual union ALL
SELECT 'ID4'       , NULL               , 'ID3'          FROM dual union ALL
SELECT 'INVALID3'  , 'ID5'              , 'ID3'          FROM dual union ALL
SELECT 'INVALID3'  , 'INVALID4'         , 'ID3'          FROM dual union ALL
SELECT 'ID5'       , 'ID6'              , 'INVALID3'     FROM dual union ALL
SELECT 'INVALID4'  , 'ID7'              , 'INVALID3'     FROM dual union ALL
SELECT 'ID6'       , NULL               , 'ID5'          FROM dual union ALL
SELECT 'ID7'       , 'ID8'              , 'INVALID4'     FROM dual union ALL
SELECT 'ID8'       , NULL               , 'ID7'          FROM dual
)

重要说明：即使我的示例显示相反的情况，“真实”表中的数据也不按连接顺序排序。

在我的表格“ OriginalSequence”中：

• 列“ KEY”是当前密钥的名称。
• 列“ Child”是当前密钥之后的密钥名称。
• “父”列是当前密钥之前的密钥名称。
• 被认为是“无效”的以“ INVALID”开头的密钥。

从层次上讲，我的示例中的数据类似于： http : //i.xomf.com/qlkgx.png

因此，我想一种方法来忽略（跳过）无效数据，以便获得以下结果：

KEY,NEW_CHILD,NEW_PARENT
ID1,ID2      ,null
ID1,ID3      ,null
ID2,null     ,ID1
ID3,ID4      ,ID1
ID3,ID5      ,ID1
ID3,ID7      ,ID1
ID4,null     ,ID3
ID5,ID6      ,ID3
ID6,null     ,ID5
ID7,ID8      ,ID3
ID8,null     ,ID7

http://i.xomf.com/dfsdq.png

理想情况下，我想避免使用PL / SQL并继续使用SQL，但如果无法解决，我将采用PL / SQL解决方案！

谢谢！

Answer 1

WITH invalid_removed AS (
  -- remove the invalid entries
  SELECT CONNECT_BY_ROOT parent AS key,
         child
  FROM   OriginalSequence
  WHERE  child NOT LIKE 'INVALID%'
  OR     child IS NULL
  CONNECT BY PRIOR child = key
             AND key LIKE 'INVALID%'
  START WITH (   parent IS null
              OR parent NOT LIKE 'INVALID%'
             )
             AND key LIKE 'INVALID%'

UNION ALL

  -- include the rows which are not invalid
  SELECT key,
         child
  FROM   OriginalSequence
  WHERE  key NOT LIKE 'INVALID%'
  AND    (child NOT LIKE 'INVALID%'
          OR child IS NULL)

UNION ALL

  -- include the root (if not included by first query)
  SELECT parent AS key,
         key AS child
  FROM   OriginalSequence
  WHERE  parent IS NULL
  AND    key NOT LIKE 'INVALID%'
)
SELECT key,
       child,
       PRIOR key AS parent
FROM   invalid_removed
CONNECT BY PRIOR child = key
START WITH key IS NULL
ORDER BY key ASC NULLS FIRST, child ASC NULLS FIRST;

SQLFIDDLE