Oracle XMLTABLE 函数。如何合并具有相同名称的节点？

Question

对帖子进行了编辑以提供一个可重复的最小示例

我正在寻找一种方法来连接所有名称节点（可能是 2-3-4 等）以及它们之间的空间。以下示例给出错误ORA-19279: XPTY0004 - XQuery dynamic type mismatch: expected singleton sequence - got multi-item sequence。我知道这是因为有多个名称节点。

我尝试替换

"name" VARCHAR2(50) PATH 'name' 与

"name" VARCHAR2(50) PATH 'name[1]' 只会给出第一个值。这会消除错误，但不会将它们连接在一起。

WITH XML_T (XML_FILE_DATA) AS (SELECT '<breakfast_menu>
    <food>
        <name>Belgian Waffles</name>
        <name>Cake</name>
        <price>$5.95</price>
        <calories>650</calories>
    </food>
    <food>
        <name>Belgian Waffles(2)</name>
        <name>Cake(2)</name>
        <price>$5.95(2)</price>
        <calories>650(2)</calories>
    </food>
</breakfast_menu>' FROM DUAL)
SELECT x.*
  FROM XML_T,
       XMLTABLE ('/breakfast_menu/food'
                 PASSING xmltype (XML_T.XML_FILE_DATA)
                 COLUMNS    "name"        VARCHAR2(50) PATH 'name',
                            "price"       VARCHAR2(50) PATH 'price',
                            "calories"    VARCHAR2(50) PATH 'calories') X;   

我希望能够获取 2 个名称并将它们合并到一个列中。期望的输出：

+-------------------------+-------------+-------------+
| name                    |       price |    calories |
+-------------------------+-------------+-------------+
| Belgian Waffles Cake    |       $5.95 |         650 |
| Belgian Waffles Cake(2) |    $5.95(2) |      650(2) |
+-------------------------+-------------+-------------+

@Padders Answer 解决了这个问题。

Answer 1

您可以在 PATH 字符串中使用 Oracle 对 xquery 表达式的支持，例如

SELECT xt.*
FROM   xml_t x,
       XMLTABLE (
           'breakfast_menu/food'
           PASSING x.xml_file_data
           COLUMNS
              names VARCHAR2 (4000) PATH 'string-join(name," ")',
              price VARCHAR2 (50) PATH 'price',
              calories VARCHAR2 (50) PATH 'calories') xt;  

Answer 2

您可以像这样在 XPath 选择器中指定要查找的 名称：

WITH xml_t (xml_file_data) AS (SELECT '<breakfast_menu>
    <food>
        <name>Belgian Waffles</name>
        <name>Cake</name>
        <price>$5.95</price>
        <calories>650</calories>
    </food>
    <food>
        <name>Belgian Waffles(2)</name>
        <name>Cake(2)</name>
        <price>$5.95(2)</price>
        <calories>650(2)</calories>
    </food>
</breakfast_menu>' FROM DUAL)
SELECT TRIM (name1 || ' ' || name2 || ' ' || name3 || ' ' || name4) AS combined_names, x.*
  FROM xml_t,
       XMLTABLE ('/breakfast_menu/food'
                 PASSING xmltype (XML_T.XML_FILE_DATA)
                 COLUMNS name1 VARCHAR2 (50) PATH 'name[1]',
                         name2 VARCHAR2 (50) PATH 'name[2]',
                         name3 VARCHAR2 (50) PATH 'name[3]',
                         name4 VARCHAR2 (50) PATH 'name[4]',
                         price VARCHAR2 (50) PATH 'price',
                         calories VARCHAR2 (50) PATH 'calories') X;



               COMBINED_NAMES                 NAME1      NAME2    NAME3    NAME4       PRICE    CALORIES
_____________________________ _____________________ __________ ________ ________ ___________ ___________
Belgian Waffles Cake          Belgian Waffles       Cake                         $5.95       650
Belgian Waffles(2) Cake(2)    Belgian Waffles(2)    Cake(2)                      $5.95(2)    650(2)