Oracle 中的向上树遍历

Question

我在 OracleDB 12c 中有以下表格

类别Table：

+-------------+-----------+---------------------+
| CATEGORY_ID | PARENT_ID |     DESCRIPTION     |
+-------------+-----------+---------------------+
|           1 | (null)    | Category 1          |
|           2 | (null)    | Category 2          |
|           3 | (null)    | Category 3          |
|           4 | (null)    | Category 4          |
|           5 | 1         | Subcategory level 1 |
|           6 | 5         | Subcategory level 2 |
|           7 | 6         | Subcategory level 3 |
|           8 | 2         | Subcategory level 1 |
|           9 | 3         | Subcategory level 1 |
|          10 | 4         | Subcategory level 1 |
+-------------+-----------+---------------------+

用户Table：

+---------+-------+
| USER_ID | NAME  |
+---------+-------+
|       1 | Ben   |
|       2 | Frank |
+---------+-------+

订单Table：

+----------+-------------+---------+
| ORDER_ID | CATEGORY_ID | USER_ID |
+----------+-------------+---------+
|        1 |           1 |       1 |
|        2 |           7 |       2 |
+----------+-------------+---------+

我想获取给定 order_id 的每个类别和子类别的信息。

例如：

给定 order_id = 2，找到每个类别和子类别：

+-------------+-----------+---------------------+
| CATEGORY_ID | PARENT_ID |     DESCRIPTION     |
+-------------+-----------+---------------------+
|           1 | (null)    | Category 1          |
|           5 | 1         | Subcategory level 1 |
|           6 | 5         | Subcategory level 2 |
|           7 | 6         | Subcategory level 3 |
+-------------+-----------+---------------------+

我尝试使用 CONNECT BY，如下面 SQLFiddle 所示，但它给了我很多 "useless" 行。

Answer 1

是这样的吗？

SQL> select c.category_id, c.parent_id, c.description
  2  from categories c
  3  start with c.category_id = (select o.category_id from orders o
  4                              where o.order_id = 2)
  5  connect by c.category_id = prior c.parent_id
  6  order by c.category_id;

CATEGORY_ID  PARENT_ID DESCRIPTION
----------- ---------- -------------------------
          1            Category 1
          5          1 Subcategory level 1
          6          5 Subcategory level 2
          7          6 Subcategory level 3

SQL>

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