Oracle SQL生成嵌套的xml

我想通过在Oracle的PLSQL函数中只使用一个查询来获取嵌套 XML.

数据库(无法更改)：

表’products_details’：

`attr_id` | `attribute`    | `fk_parent_id`(Foreign key on `attr_id`)
-------------------------------------------------------------------------------
1         |  name           | null
3         |  sizes          | null
4         |  size_women     | 3
5         |  size_man       | 3
6         |  size_dimension | 3

表’product_contents’：

`detail`      | `value`   |  variation_number  | `product_id` (doesnt matter)
-------------------------------------------------------------------------------
name          |  Tshirt   | null               | 1000
price         |  14.99    | null               | 1000
size_man      |  XL       | 1                  | 1000
size_women    |  L        | 1                  | 1000
size_dimesion |  21x25cm  | 1                  | 1000
size_man      |  M        | 2                  | 1000
size_women    |  S        | 2                  | 1000
size_dimesion |  14x16cm  | 2                  | 1000
...

正如您所看到的,每种产品只有一些选项(名称,价格),但也有一些选项(size_man,size_woman ……)是变体,每种产品可以存在多次.

我想要的是一个XML：

<attribute detail="name">Tshirt</attribute>
<attribute detail="price">14.99</attribute>
<attribute detail="sizes">
      <row variation_number="1">
          <attribute detail="size_man">XL</attribute>
          <attribute detail="size_women">L</attribute>
          ...
      </row>
      <row variation_number="2">
          <attribute detail="size_man">M</attribute>
          <attribute detail="size_women">S</attribute>
      </row>
</attribute>

到目前为止我尝试过的(当然不是真的有效)：

SELECT 
(
    XMLELEMENT(  "attribute",XMLATTRIBUTES(pc.detail as "detail"),(SELECT XMLAGG
                (

                XMLELEMENT("row",XMLATTRIBUTES(pc.variant_number as "variation_number") )

                )

                FROM product_contents pc 

                JOIN product_details pd ON pc.detail = pd.attribute and pc.product_id = '1000'

                WHERE pd.fk_parent_id = pd.ID

              )      

).getClobVal() CONTENT

FROM product_details pd   
pd.fk_parent_id is null
order by pd.attribute;

我怎么能用一个查询来做到这一点？

解决方法

WITH
  -- "memory table"
  product_details AS (
    SELECT 1 attr_id,'name' attr,null parent_id FROM dual UNION ALL 
    SELECT 2,'price',null FROM dual UNION ALL 
    SELECT 3,'sizes',null FROM dual UNION ALL 
    SELECT 4,'size_women',3 FROM dual UNION ALL 
    SELECT 5,'size_man',3 FROM dual UNION ALL 
    SELECT 6,'size_dimension',3 FROM dual
  ),-- "memory table"
  product_contents AS (
    SELECT 'name' detail,'Tshirt' value,null variation,1000 product_id FROM dual UNION ALL
    SELECT 'price','14.99',null,1000 FROM dual UNION ALL
    SELECT 'size_man','XL',1,1000 FROM dual UNION ALL
    SELECT 'size_women','L',1000 FROM dual UNION ALL
    SELECT 'size_dimesion','21x25cm','M',2,'S','14x16cm',1000 FROM dual
  ),product_contents_xml AS (
    SELECT   
      variation,detail,XMLELEMENT(
        "attribute",XMLATTRIBUTES(detail as "detail"),value
      ) attr,product_id
    FROM product_contents
  ),attrs AS (
      SELECT
        pc.attr
      FROM
        product_contents_xml pc JOIN 
        product_details pd ON pc.detail = pd.attr and pc.product_id = 1000
      WHERE
        pd.parent_id IS NULL

      UNION ALL

    SELECT
      XMLELEMENT("attribute",XMLATTRIBUTES(t.attr AS "detail"),XMLAGG(t.value)) attr
    FROM (  
          SELECT
            parent.attr,XMLELEMENT("row",XMLATTRIBUTES(pc.variation as "variation_number"),XMLAGG(pc.attr)) value
          FROM
            product_contents_xml pc JOIN 
            product_details pd ON pc.detail = pd.attr and pc.product_id = 1000 JOIN
            product_details parent ON parent.attr_id = pd.parent_id
          WHERE
            pd.parent_id IS NOT NULL
          GROUP BY
            parent.attr,pc.variation
    ) t
    GROUP BY t.attr
  )
SELECT XMLAGG(attr) FROM attrs

attrs视图分为两部分 – 一部分用于没有parent_id的属性,另一部分用于具有parent_id的部分.

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