• Chapter 1: Getting Started with Stylus Studio®
• Chapter 2: Editing and Querying XML
• Chapter 3: Converting Non-XML Files to XML
• Chapter 4: Working with XSLT
• Chapter 5: Creating XSLT Using the XSLT Mapper
• Chapter 6: Debugging Stylesheets
• Chapter 7: Defining XML Schemas
• Chapter 8: Defining Document Type Definitions
• Chapter 9: Writing XPath Expressions
• Chapter 10: Working with XQuery in Stylus Studio
  • Getting Started with XQuery in Stylus Studio
  • An XQuery Primer
    • What is XQuery For?
    • Your First XQueries
    • Accessing XML Documents with XQuery
    • XQuery and XPath
    • Introduction to FLWOR Expressions
    • Generating XML Output with XQuery
    • Accessing Databases with XQuery
  • Understanding FLWOR Expressions
  • Building an XQuery Using the Mapper
  • Working with the XQuery collection() Function
  • Debugging XQuery Documents
  • Using DataDirect XQuery® Execution Plans
  • Creating an XQuery Scenario
  • Generating XQuery Documentation
  • Using XQuery to Invoke a Web Service
  • Using Web Services in XQuery
  • Generating Java Code for XQuery
  • Generating C# Code for XQuery
• Chapter 11: Composing Web Service Calls
• Chapter 12: Working with WSDL Documents
• Chapter 13: Building XML Pipelines
• Chapter 14: Publishing XML Data
• Chapter 15: Integrating with Third-Party File Systems
• Chapter 16: Extending Stylus Studio
• Chapter 17: The Stylus Studio Java API
• Chapter 18: Stylus Studio GUI Reference

Home > Online Product Documentation > Table of Contents > Generating XML Output with XQuery

Generating XML Output with XQuery

So far all the queries we have written have selected nodes in the source document. We have shown the results as if the system copies the nodes to create some kind of result document, and if you execute the XQuery in Stylus Studio or run Saxon from the command line that is exactly what happens. But this is simply a default mode of execution. In a real application you want control over the form of the output document, which might well be the input to another application - perhaps the input to an XSLT transformation or even another query.

XQuery allows the structure of the result document to be defined using an XML-like notation. Here is an example that fleshes out our previous query with some XML markup:

declare variable $firstName as xs:string external;
               
<videos featuring="{$firstName}">
               
{
               
   let $doc := .
               
   for $v in $doc//video,
               
      $a in $doc//actors/actor
               
   where ends-with($a, $firstName) 
               
and $v/actorRef = $a/@id
               
   order by $v/year
               
   return
               
      <video year="{$v/year}">
               
         {$v/title}
               
      </video>
               
}
               
</videos>
               

            

We have also changed the query so that the actor's first name is now an externally defined parameter. This makes the query reusable. The way parameters are supplied varies from one XQuery processor to another. In Stylus Studio, select XQuery > Scenario Properties; click the Parameter Values tab, and Stylus Studio provides an area to specify values for any variables defined in the XQuery.

Figure 293. Entering Values for XQuery Variables

Enter "Lisa", in quotes (Stylus Studio expects an expression, so if the quotes are omitted, this value would be taken as a reference to an element named <Lisa>).

If instead you are running Saxon from the command line, you can enter:

              java net.sf.saxon.Query sample.xquery firstName=Lisa
               

            

Either way, our XQuery returns the following result:

<videos featuring="Lisa">
               
   <video year="1999">
               
      <title>Enemy of the State</title>
               
   </video>
               
   <video year="1999">
               
      <title>Clerks</title>
               
   </video>
               
</videos> 
               

            

As you might recall from our previous XQuery, this version of the XQuery is not especially well-designed as it returns videos featuring different actresses named Lisa. Take some time and modify the XQuery to see if you can improve it.