title: How to modify existing XML file with XmlDocument and XmlNode in C#
body: <p>I already implemented to create the XML file below with <strong>XmlTextWriter</strong> when application initialization. </p>
  
  <p>And know I don't know how to update the childNode id value with <strong>XmlDocument</strong> &amp; <strong>XmlNode</strong>.  </p>
  
  <p>Is there some property to update the id value? I tried <em>InnerText</em> but failed. thank you.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;Equipment xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"&gt;
    &lt;License licenseId="" licensePath=""/&gt;
    &lt;DataCollections&gt;
      &lt;GroupAIDs&gt;
        &lt;AID id="100"&gt;
          &lt;Variable id="200"/&gt;
          &lt;Variable id="201"/&gt;
        &lt;/AID&gt;
        &lt;AID id=""&gt;
          &lt;Variable id="205"/&gt;
        &lt;/AID&gt;
        &lt;AID id="102"/&gt;
      &lt;/GroupAIDs&gt;
      &lt;GroupBIDs&gt;
        &lt;BID id="2000"&gt;
          &lt;AID id="100"/&gt;
        &lt;/BID&gt;
        &lt;BID id="2001"&gt;
          &lt;AID id="101"/&gt;
          &lt;AID id="102"/&gt;
        &lt;/BID&gt;
      &lt;/GroupBIDs&gt;
      &lt;GroupCIDs&gt;
        &lt;BID id="8"/&gt;
        &lt;BID id="9"/&gt;
        &lt;BID id="10"/&gt;
      &lt;/GroupCIDs&gt;
    &lt;/DataCollections&gt;
  &lt;/Equipment&gt;
  </code></pre>