xquery Getting started with xquery Extracting XML Data

Example

To address data from an XML input, XQuery uses XPath.
It makes it easy to filter data and restructure it.

Given the following XML input

<?xml version="1.0" encoding="UTF-8"?>
<applications>
  <application>
    <id>MyApp</id>
    <name>My Application</name>
    <version>1.0</version>
  </application>
  <application>
    <id>SomeApp</id>
    <name>Some Application</name>
    <version>4.2</version>
  </application>
  <application>
    <id>TheOtherApp</id>
    <name>That one</name>
    <version>13.37</version>
  </application>
</applications>    

The following XQuery code will extract the application whose id is MyApp :

/applications/application[id='MyApp']

It produces the following XML document :

<?xml version="1.0" encoding="UTF-8"?>
<application>
  <id>MyApp</id>
  <name>My Application</name>
  <version>1.0</version>
</application>

And this code will extract the applications whose version is lower than 10, outputting them in a <oldApplications> tag :

    <oldApplications>{/applications/application[version < 10]}</oldApplications> 

It procudes the following XML document :

<?xml version="1.0" encoding="UTF-8"?>
<oldApplications>
  <application>
    <id>MyApp</id>
    <name>My Application</name>
    <version>1.0</version>
  </application>
  <application>
    <id>SomeApp</id>
    <name>Some Application</name>
    <version>4.2</version>
  </application>
</oldApplications>