反转存储层次结构的逗号分隔列答案

【问题标题】：Reverse a comma separated column that stores hierarchy反转存储层次结构的逗号分隔列
【发布时间】：2016-05-03 08:00:04
【问题描述】：

我有一个从下表创建 H_TREE 列的查询，

+------+--------+
| UNIT | M_UNIT |
+------+--------+
|   10 |     12 |
|   15 |     19 |
|   12 |     16 |
|   13 |     15 |
|   19 |     14 |
|   14 |     11 |
+------+--------+

以下是我正在使用的查询，

WITH data (unit, m_unit) AS (
  SELECT 10, 12 FROM dual UNION ALL
  SELECT 15, 19 FROM dual UNION ALL
  SELECT 12, 16 FROM dual UNION ALL
  SELECT 13, 15 FROM dual UNION ALL
  SELECT 19, 14 FROM dual UNION ALL
  SELECT 14, 11 FROM dual)
SELECT
    unit,
    m_unit,
    unit || ',' || listagg(root_unit, ',') WITHIN GROUP (ORDER BY depth) h_tree
FROM (
SELECT
    id, unit, m_unit,
    LEVEL depth, CONNECT_BY_ROOT m_unit root_unit
FROM
    (SELECT ROWNUM id, unit, m_unit FROM data) data
CONNECT BY
    PRIOR unit = m_unit)
GROUP BY
    id,
    unit,
    m_unit

以上查询返回，

+------+--------+----------------+
| UNIT | M_UNIT |     H_TREE     |
+------+--------+----------------+
|   10 |     12 | 10,12,16       |
|   15 |     19 | 15,19,14,11    |
|   12 |     16 | 12,16          |
|   13 |     15 | 13,15,19,14,11 |
|   19 |     14 | 19,14,11       |
|   14 |     11 | 14,11          |
+------+--------+----------------+

我想反转 H_TREE 列的顺序，使其如下所示，

+------+--------+----------------+
| UNIT | M_UNIT |     H_TREE     |
+------+--------+----------------+
|   10 |     12 | 16,12,10       |
|   15 |     19 | 11,14,19,15    |
|   12 |     16 | 16,12          |
|   13 |     15 | 11,14,19,15,13 |
|   19 |     14 | 11,14,19       |
|   14 |     11 | 11,14          |
+------+--------+----------------+

为了实现这一点，我需要对此现有查询进行哪些更改？

根据 cmets: WITHIN GROUP (ORDER BY depth DESC) 给我以下结果，

+------+--------+----------------+
| UNIT | M_UNIT |     H_TREE     |
+------+--------+----------------+
| 10   |  12    |  10,16,12      |
| 15   |  19    |  15,11,14,19   |
| 12   |  16    |  12,16         |
| 13   |  15    |  13,11,14,19,15|
| 19   |  14    |  19,11,14      |
| 14   |  11    |  14,11         |
+------+--------+----------------+

【问题讨论】：

WITHIN GROUP (ORDER BY depth DESC) 在此处添加 DESC
这不会返回我在查询中提到的顺序。谢谢。
您能发布“WITHIN GROUP (ORDER BY depth DESC)”的结果吗？
我已经在我的问题中添加了结果谢谢@haytem

标签： sql oracle hierarchy hierarchical-data

【解决方案1】：

试试：

WITH data (unit, m_unit) AS (
    SELECT 10, 12 FROM dual UNION ALL
    SELECT 15, 19 FROM dual UNION ALL
    SELECT 12, 16 FROM dual UNION ALL
    SELECT 13, 15 FROM dual UNION ALL
    SELECT 19, 14 FROM dual UNION ALL
    SELECT 14, 11 FROM dual)
SELECT
    unit,
    m_unit,
    listagg(root_unit, ',') WITHIN GROUP (ORDER BY depth desc) || ',' || unit as h_tree
FROM (
    SELECT
        id, unit, m_unit,
        LEVEL depth, CONNECT_BY_ROOT m_unit root_unit
    FROM
        (SELECT ROWNUM id, unit, m_unit FROM data) data
    CONNECT BY
        PRIOR unit = m_unit)
GROUP BY
    id,
    unit,
    m_unit

【讨论】：

此查询抛出：ORA-00979: not a GROUP BY expression 00979. 00000 - "not a GROUP BY expression" *原因：*操作：第 10 行错误，第 5 列
谢谢@Haytem，它运行良好。感谢您的帮助。