使用 where 子句中的属性名称从 XML Clob 中提取数据

Question

我们有一个名为JOURNALARTICLE 的表，其列CONTENT 将XML 数据存储为CLOB。

<?xml version="1.0"?>
<root available-locales="en_US" default-locale="en_US">
    <dynamic-element name="group_html_title" type="text" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[Industrial AC Drives]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="group_image" type="document_library" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[/documents/20184/40787/Industrial-AC-Drives--Fan-and-Pump_Drives.png/8a1e761d-1cac-49aa-8212-fa3943204449?t=1437389273031]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="product_type" type="list" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[Drives]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="page_banner" type="list" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[a2cdb3ca-8872-4d08-a6ee-00b84495e0e0]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="access_groups" type="list" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="short_copy" type="text_area" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[<p>Drives that offer a broad range of control modes, features, options, and packaging, for use in factory automation processes and industrial OEM machines.&nbsp;<a href="javascript:void(0);" onclick="showDocumentsStaticPopup('eLM.J1000.01')" style="line-height: 1.5;">Test POPUP</a>&nbsp;<a href="javascript:void(0);" onclick="showDocumentsStaticPopup('eLM.J1000.01')" style="line-height: 1.5;">Test POPUP</a></p>]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="html_body" type="text_area" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="group_active" type="boolean" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[true]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="page_meta_description" type="text" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[Yaskawa's Family of AC Drives are designed for industrial automation applications. These adjustable frequency drives are typically capable of network communications, supported by software tools for parameter management and able to accept custom software]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="page_meta_keywords" type="text" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[Yaskawa, AC_drive, AC, VFD, industrial_automation, industrial_drives, variable_frequency_drive, AC_drives]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="business_weightage" type="ddm-number" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[5000]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="clickable_in_left_navigation" type="boolean" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[true]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="clickable_in_menu" type="boolean" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[true]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="visible_in_left_navigation" type="boolean" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[true]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="visible_in_menu" type="boolean" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[true]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="external_url" type="text" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[]]></dynamic-content>
    </dynamic-element>
    <dynamic-element name="shared_with_site" type="list" index-type="keyword" index="0">
        <dynamic-content language-id="en_US"><![CDATA[]]></dynamic-content>
    </dynamic-element>
</root>

我想从属性名称为"group_html_title" 的dynamic-content 节点中提取文本，因此它应该返回值“工业交流驱动器”。

我该怎么做？

Answer 1

您可以使用 XMLQuery 或 XMLTable：

select x.content
from journalarticle j
cross join xmltable ('/root/dynamic-element[@name="group_html_title"]'
  passing xmltype(j.content)
  columns content varchar2(4000) path 'dynamic-content'
) x;

CONTENT                                                                        
--------------------------------------------------------------------------------
Industrial AC Drives                                                            

XPath 在root 下查找dynamic-element 节点，并通过[@name=...] 部分将其限制为属性具有您想要的名称的节点。然后它从任何匹配的元素节点下的dynamic-content节点中提取节点值。

Read more in the documentation.

问题标题提到了 where 子句。您可以使用 XMLTable 将所有数据提取到列中，然后根据其中之一进行过滤，或者您可以直接在 where 子句中使用 XMLQuery：

select *
from journalarticle j
where xmlquery('for $i in /root/dynamic-element[@name="group_html_title"]
  where $i/dynamic-content = "Industrial AC Drives"
  return $i'
  passing xmltype(j.content) returning content) is not null;

或者将两者结合起来，使用 XMLTable 获取您想要的数据，然后使用 XMLQuery 来首先过滤基表行。