XML Tutorial

XML HOME XML Introduction XML How to use XML Tree XML Syntax XML Elements XML Attributes XML Namespaces XML Display XML HttpRequest XML Parser XML DOM XML XPath XML XSLT XML XQuery XML XLink XML Validator XML DTD XML Schema XML Server XML Examples


AJAX Introduction AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples


DOM Introduction DOM Nodes DOM Accessing DOM Node Info DOM Node List DOM Traversing DOM Navigating DOM Get Values DOM Change Nodes DOM Remove Nodes DOM Replace Nodes DOM Create Nodes DOM Add Nodes DOM Clone Nodes DOM Examples

XPath Tutorial

XPath Introduction XPath Nodes XPath Syntax XPath Axes XPath Operators XPath Examples

XSLT Tutorial

XSLT Introduction XSL Languages XSLT Transform XSLT <template> XSLT <value-of> XSLT <for-each> XSLT <sort> XSLT <if> XSLT <choose> XSLT Apply XSLT on the Client XSLT on the Server XSLT Edit XML XSLT Examples

XQuery Tutorial

XQuery Introduction XQuery Example XQuery FLWOR XQuery HTML XQuery Terms XQuery Syntax XQuery Add XQuery Select XQuery Functions


DTD Introduction DTD Building Blocks DTD Elements DTD Attributes DTD Elements vs Attr DTD Entities DTD Examples

XSD Schema

XSD Introduction XSD How To XSD <schema> XSD Elements XSD Attributes XSD Restrictions

XSD Complex

XSD Elements XSD Empty XSD Elements Only XSD Text Only XSD Mixed XSD Indicators XSD <any> XSD <anyAttribute> XSD Substitution XSD Example

XSD Data

XSD String XSD Date XSD Numeric XSD Misc XSD Reference

Web Services



DOM Node Types DOM Node DOM NodeList DOM NamedNodeMap DOM Document DOM Element DOM Attribute DOM Text DOM CDATA DOM Comment DOM XMLHttpRequest DOM Parser XSLT Elements XSLT/XPath Functions

XQuery Functions

XQuery 1.0, XPath 2.0, and XSLT 2.0 share the same functions library.

XQuery Functions

XQuery is built on XPath expressions. XQuery 1.0 and XPath 2.0 share the same data model and support the same functions and operators.

XPath Operators

XPath Functions

You can also define your own functions in XQuery.

XQuery Data Types

XQuery shares the same data types as XML Schema 1.0 (XSD).

XSD String

XSD Date

XSD Numeric

XSD Misc

Examples of Function Calls

A call to a function can appear where an expression may appear. Look at the examples below:

Example 1: In an element


Example 2: In the predicate of a path expression


Example 3: In a let clause

let $name := (substring($booktitle,1,4))

XQuery User-Defined Functions

If you cannot find the XQuery function you need, you can write your own.

User-defined functions can be defined in the query or in a separate library.


declare function prefix:function_name($parameter as datatype)
as returnDatatype
 ...function code here...

Notes on user-defined functions:

  • Use the declare function keyword
  • The name of the function must be prefixed
  • The data type of the parameters are mostly the same as the data types defined in XML Schema
  • The body of the function must be surrounded by curly braces

Example of a User-defined Function Declared in the Query

declare function local:minPrice($p as xs:decimal?,$d as xs:decimal?)
as xs:decimal?
let $disc := ($p * $d) div 100
return ($p - $disc)

Below is an example of how to call the function above: