Oracle UpdateXML()会更改XML结构吗?

问题描述

当我呼叫UpdateXML()时，我发现空节点正在转换为简写XML.是否有一种方法可以防止UpdateXML()以这种方式运行，也许是一个标志或设置或备用XPath表达式来告诉它保留原始结构?

/* Example 1 */
SELECT UpdateXML(xmlData, '/TEST/VALUE/text()', 'hello') as "Example 1"
  FROM (SELECT XMLType('<TEST><VALUE>hi</VALUE></TEST>') as xmlData
          FROM DUAL);

Example 1
---------
<TEST><VALUE>hello</VALUE></TEST>


/* Example 2 */
SELECT UpdateXML(xmlData, '/TEST/VALUE/text()', 'hello') as "Example 2"
  FROM (SELECT XMLType('<TEST><VALUE></VALUE></TEST>') as xmlData
          FROM DUAL);

Example 2
---------
<TEST><VALUE/></TEST>

我想看的东西

/* Desired Output, vs. Example 2 */
SELECT UpdateXML(xmlData, '/TEST/VALUE/text()', 'hello') as "Desired Output"
  FROM (SELECT XMLType('<TEST><VALUE></VALUE></TEST>') as xmlData
          FROM DUAL);

Desired Output
--------------
<TEST><VALUE></VALUE></TEST>

解决方案

我认为您可以通过将空文本替换为临时值，更新所有其他文本，然后将临时值替换为空值来避免此问题. /p>

我不了解XPath，也许有更好的方法来做到这一点，但这似乎行得通:

SELECT
    --#3: Replace the temporary value with null, this keeps the start and end tag
    UpdateXML(
        --#2: Replace everything but the temporary value
        UpdateXML(
            --#1: Replace empty text with a temporary value
            UpdateXML(xmlData, '/TEST/VALUE[not(text())]', '<VALUE>TEMPORARY VALUE</VALUE>')
        ,'/TEST/VALUE[text()!="TEMPORARY VALUE"]/text()', 'hello')
    ,'/TEST/VALUE[text()="TEMPORARY VALUE"]/text()', null) examle
FROM (SELECT XMLType('<TEST><VALUE>hi</VALUE><VALUE>hola</VALUE><VALUE></VALUE></TEST>') as xmlData FROM DUAL);

When I call UpdateXML() I find that empty nodes are being converted to shorthand XML. Is there a way to prevent UpdateXML() from behaving this way, perhaps a flag or setting or alternate XPath expression to tell it to preserve the original structure?

/* Example 1 */
SELECT UpdateXML(xmlData, '/TEST/VALUE/text()', 'hello') as "Example 1"
  FROM (SELECT XMLType('<TEST><VALUE>hi</VALUE></TEST>') as xmlData
          FROM DUAL);

Example 1
---------
<TEST><VALUE>hello</VALUE></TEST>


/* Example 2 */
SELECT UpdateXML(xmlData, '/TEST/VALUE/text()', 'hello') as "Example 2"
  FROM (SELECT XMLType('<TEST><VALUE></VALUE></TEST>') as xmlData
          FROM DUAL);

Example 2
---------
<TEST><VALUE/></TEST>

What I would like to see:

/* Desired Output, vs. Example 2 */
SELECT UpdateXML(xmlData, '/TEST/VALUE/text()', 'hello') as "Desired Output"
  FROM (SELECT XMLType('<TEST><VALUE></VALUE></TEST>') as xmlData
          FROM DUAL);

Desired Output
--------------
<TEST><VALUE></VALUE></TEST>

解决方案

I think you can avoid the problem by replacing empty text with a temporary value, updating all the other text, and then replacing the temporary value with a null.

I don't understand XPath, there's probably a much better way to do this, but this seems to work:

SELECT
    --#3: Replace the temporary value with null, this keeps the start and end tag
    UpdateXML(
        --#2: Replace everything but the temporary value
        UpdateXML(
            --#1: Replace empty text with a temporary value
            UpdateXML(xmlData, '/TEST/VALUE[not(text())]', '<VALUE>TEMPORARY VALUE</VALUE>')
        ,'/TEST/VALUE[text()!="TEMPORARY VALUE"]/text()', 'hello')
    ,'/TEST/VALUE[text()="TEMPORARY VALUE"]/text()', null) examle
FROM (SELECT XMLType('<TEST><VALUE>hi</VALUE><VALUE>hola</VALUE><VALUE></VALUE></TEST>') as xmlData FROM DUAL);

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