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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 XML Quiz XML Certificate

XML AJAX

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XML DOM

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

XML DTD

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

XSD Data Types

XSD String XSD Date/Time XSD Numeric XSD Misc XSD Reference

Web Services

XML Services XML WSDL XML SOAP XML RDF XML RSS

References

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 FLWOR Expressions

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What is FLWOR?

FLWOR (pronounced "flower") is an acronym for "For, Let, Where, Order by, Return".

  • For - selects a sequence of nodes
  • Let - binds a sequence to a variable
  • Where - filters the nodes
  • Order by - sorts the nodes
  • Return - what to return (gets evaluated once for every node)

The XML Example Document

We will use the "books.xml" document in the examples below (same XML file as in the previous chapter).

View the "books.xml" file in your browser.

How to Select Nodes From "books.xml" With FLWOR

Look at the following path expression:

doc("books.xml")/bookstore/book[price>30]/title

The expression above will select all the title elements under the book elements that are under the bookstore element that have a price element with a value that is higher than 30.

The following FLWOR expression will select exactly the same as the path expression above:

for $x in doc("books.xml")/bookstore/book
where $x/price>30
return $x/title

The result will be:

<title lang="en">XQuery Kick Start</title>
<title lang="en">Learning XML</title>

With FLWOR you can sort the result:

for $x in doc("books.xml")/bookstore/book
where $x/price>30
order by $x/title
return $x/title

The for clause selects all book elements under the bookstore element into a variable called $x.

The where clause selects only book elements with a price element with a value greater than 30.

The order by clause defines the sort-order. Will be sort by the title element.

The return clause specifies what should be returned. Here it returns the title elements.

The result of the XQuery expression above will be:

<title lang="en">Learning XML</title>
<title lang="en">XQuery Kick Start</title>

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