• 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
  • About the XPath Processor
  • Sample Data for Examples and Testing
  • Getting Started with Queries
  • Specifying the Nodes to Evaluate
  • Handling Strings and Text
  • Specifying Boolean Expressions and Functions
  • Specifying Number Operations and Functions
  • Comparing Values
  • Finding a Particular Node
  • Obtaining a Union
  • Obtaining Information About a Node or a Node Set
  • Using XPath Expressions in Stylesheets
  • Accessing Other Documents During Query Execution
  • XPath Quick Reference
• Chapter 10: Working with XQuery in Stylus Studio
• Chapter 11: Composing Web Service Calls
• Chapter 12: Accessing Relational Data as XML
• Chapter 13: Extending Stylus Studio
• Chapter 14: Stylus Studio Reference

Home > Online Product Documentation > Table of Contents > Calling Functions in Queries

Calling Functions in Queries

The XPath processor provides many functions that you can call in a query. This section provides some examples to give you a sense of how functions in queries work. Many subsequent sections provide information about invoking functions in queries. For a complete list of the functions you can call in a query, see XPath Functions Quick Reference.

Following is a query that returns a number that indicates how many book elements are in the document:

count(//book)
               

            

In format descriptions, a question mark that follows an argument indicates that the argument is optional. For example:

string substring(string, number, number?) 
               

            

This function returns a string. The name of the function is substring. This function takes two required arguments (a string followed by a number) and one optional argument (a number).