XQuery First Example

Here, the XML document is named as courses.xml and xqy file is named as courses.xqy

courses.xml

<?xml version="1.0" encoding="UTF-8"?>
<courses>   
   <course category="JAVA">
      <title lang="en">Learn Java in 3 Months.</title>
      <trainer>Sonoo Jaiswal</trainer>
      <year>2008</year>
      <fees>10000.00</fees>
   </course>  
    <course category="Dot Net">
      <title lang="en">Learn Dot Net in 3 Months.</title>
      <trainer>Vicky Kaushal</trainer>
      <year>2008</year>
      <fees>10000.00</fees>
   </course>
    <course category="C">
      <title lang="en">Learn C in 2 Months.</title>
      <trainer>Ramesh Kumar</trainer>
      <year>2014</year>
      <fees>3000.00</fees>
   </course>
    <course category="XML">
      <title lang="en">Learn XML in 2 Months.</title>
      <trainer>Ajeet Kumar</trainer>
      <year>2015</year>
      <fees>4000.00</fees>
   </course>  
</courses>

courses.xqy

for $x in doc("courses.xml")/courses/course
where $x/fees>5000
return $x/title

This example will display the title elements of the courses whose fees are greater than 5000.

Create a Java based XQuery executor program to read the courses.xqy, passes it to the XQuery expression processor, and executes the expression. After that the result will be displayed.

XQueryTester.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

import javax.xml.xquery.XQConnection;
import javax.xml.xquery.XQDataSource;
import javax.xml.xquery.XQException;
import javax.xml.xquery.XQPreparedExpression;
import javax.xml.xquery.XQResultSequence;

import com.saxonica.xqj.SaxonXQDataSource;

public class XQueryTester {
   public static void main(String[] args){
      try {
         execute();
      }
      
      catch (FileNotFoundException e) {
         e.printStackTrace();
      }
      
      catch (XQException e) {
         e.printStackTrace();
      }
   }

   private static void execute() throws FileNotFoundException, XQException{
      InputStream inputStream = new FileInputStream(new File("courses.xqy"));
      XQDataSource ds = new SaxonXQDataSource();
      XQConnection conn = ds.getConnection();
      XQPreparedExpression exp = conn.prepareExpression(inputStream);
      XQResultSequence result = exp.executeQuery();
       while (result.next()) {
         System.out.println(result.getItemAsString(null));
      }
   }	
}

Execute XQuery against XML

Put the above three files to a same location. We put them on desktop in a folder name XQuery2. Compile XQueryTester.java using console. You must have JDK 1.5 or later installed on your computer and classpaths are configured.

Compile:

javac XQueryTester.java

Execute:

java XQueryTester

Output: