XSLT 2.0 and Beyond

XSLT 2.0 and Beyond

Elliotte Rusty Harold

XML & Web Services 2003 London

Wednesday, March 19, 2003

elharo@metalab.unc.edu

http://www.cafeconleche.org//

Outline

Versions Covered

XPath 2.0

XPath 2.0 Goals

XPath 2.0 Requirements

XPath 1.0 Data Model

(Adapted from Jeni Tennison)

XPath 2.0 Data Model

(Adapted from Jeni Tennison)

Working with Sequences

Constructing sequences

Sequence example

<?xml version="1.0"?> 
<xsl:stylesheet version="2.0" 
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:template match="/">
    <numbers>
      <xsl:for-each select="(1 to 10)">
        <integer>
          <xsl:value-of select="."/>
        </integer>
      </xsl:for-each>
    </numbers>
  </xsl:template>

</xsl:stylesheet>

Output (modulo white space):

<?xml version="1.0" encoding="utf-8"?>
<numbers>
<integer>1</integer>
<integer>2</integer>
<integer>3</integer>
<integer>4</integer>
<integer>5</integer>
<integer>6</integer>
<integer>7</integer>
<integer>8</integer>
<integer>9</integer>
<integer>10</integer>
</numbers>

Unions of sequences

<?xml version="1.0"?> 
<xsl:stylesheet version="2.0" 
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output indent="yes"/>             
                
  <xsl:template match="/">
    <numbers>
      <xsl:for-each select='(3 to 10) | (5 to 12) | (20 to 23)'>
        <integer>
          <xsl:value-of select="."/>
        </integer>
      </xsl:for-each>
    </numbers>
  </xsl:template>

</xsl:stylesheet>

Output:

<numbers>
<integer>3</integer>
<integer>4</integer>
<integer>5</integer>
<integer>6</integer>
<integer>7</integer>
<integer>8</integer>
<integer>9</integer>
<integer>10</integer>
<integer>11</integer>
<integer>12</integer>
<integer>20</integer>
<integer>21</integer>
<integer>22</integer>
<integer>23</integer>
</numbers>

Intersections of sequences

<?xml version="1.0"?> 
<xsl:stylesheet version="2.0" 
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output indent="yes"/>             
                
  <xsl:template match="/">
    <numbers>
      <xsl:for-each select='(3 to 10) intersect (5 to 12)'>
        <integer>
          <xsl:value-of select="."/>
        </integer>
      </xsl:for-each>
    </numbers>
  </xsl:template>

</xsl:stylesheet>

Output:

<numbers>
<integer>5</integer>
<integer>6</integer>
<integer>7</integer>
<integer>8</integer>
<integer>9</integer>
<integer>10</integer>
</numbers>

Except sequences

<?xml version="1.0"?> 
<xsl:stylesheet version="2.0" 
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output indent="yes"/>             
                
  <xsl:template match="/">
    <numbers>
      <xsl:for-each select='(3 to 10) except (5 to 12)'>
        <integer>
          <xsl:value-of select="."/>
        </integer>
      </xsl:for-each>
    </numbers>
  </xsl:template>

</xsl:stylesheet>

Output:

<numbers>
  <integer>3</integer>
  <integer>4</integer>
</numbers>

Data types and the PSVI

Accessor Functions

fn:node-kind(Node)
Returns a string identifying the kind of node; i.e. "document", "element", "attribute", "text", "namespace", "processing-instruction", or "comment".
fn:name(Node)
returns zero or one QName
fn:string(Object)
returns the string value of anything
fn:data(Node)
returns a sequence of zero or more typed simple values
fn:base-uri(node)
returns the base URI of an Element or Document node
fn:unique-ID(element)
returns the unique ID of an element

Constructor Functions

Casting

Four kinds of comparison operators

Value comparison operators

General comparisons

Node comparisons

Order comparisons

Functions and operators

Arithmetic operators

Numeric comparison operators

Numeric Functions

String functions

Regular expressions

Boolean Functions

Date and time functions

Qualified Name Functions

Binary operators

Node Functions

Sequence Functions

Context Functions

Other New features in XPath 2.0

XPath Comments 

<xsl:apply-templates 
 select="{-- The difference between the context node and the 
             current node is crucial here --}
 ../composition[@composer=current()/@id]"/>

Namespace wildcards

<xsl:template match="*:set">
  This matches MathML set elements, SVG set elements, set
  elements in no namespace at all, etc. 
</xsl:template>

Can use functions as location steps

Can use parenthesized expressions as location steps

Dereference steps

For Expressions

for Example

Consider the list of weblogs at http://static.userland.com/weblogMonitor/logs.xml 

<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE foo SYSTEM "http://msdn.microsoft.com/xml/general/htmlentities.dtd">
<weblogs>
    <log>
        <name>MozillaZine</name>
        <url>http://www.mozillazine.org</url>
        <changesUrl>http://www.mozillazine.org/contents.rdf</changesUrl>
        <ownerName>Jason Kersey</ownerName>
        <ownerEmail>kerz@en.com</ownerEmail>
        <description>THE source for news on the Mozilla Organization.  DevChats, Reviews, Chats, Builds, Demos, Screenshots, and more.</description>
        <imageUrl></imageUrl>
        <adImageUrl>http://static.userland.com/weblogMonitor/ads/kerz@en.com.gif</adImageUrl>
    </log>
    <log>
        <name>SalonHerringWiredFool</name>
        <url>http://www.salonherringwiredfool.com/</url>
        <ownerName>Some Random Herring</ownerName>
        <ownerEmail>salonfool@wiredherring.com</ownerEmail>
        <description></description>
    </log>
    <log>
        <name>SlashDot.Org</name>
        <url>http://www.slashdot.org/</url>
        <ownerName>Simply a friend</ownerName>
        <ownerEmail>afriendofweblogs@weblogs.com</ownerEmail>
        <description>News for Nerds, Stuff that Matters.</description>
    </log>
</weblogs>

The changesUrl element points to a document like this: 

<?xml version="1.0"?>
<!DOCTYPE rss PUBLIC "-//Netscape Communications//DTD RSS 0.91//EN" 
                     "http://my.netscape.com/publish/formats/rss-0.91.dtd">
<rss version="0.91">
  <channel>
    <title>MozillaZine</title>
    <link>http://www.mozillazine.org/</link>
    <language>en-us</language>
    <description>Your source for Mozilla news, advocacy, interviews, builds, and more!</description>
    <copyright>Copyright 1998-2002, The MozillaZine Organization</copyright>
    <managingEditor>jason@mozillazine.org</managingEditor>
    <webMaster>jason@mozillazine.org</webMaster>
    <image>
      <title>MozillaZine</title>
      <url>http://www.mozillazine.org/image/mynetscape88.gif</url>
      <description>Your source for Mozilla news, advocacy, interviews, builds, and more!</description>
      <link>http://www.mozillazine.org/</link>
    </image>

    <item>
      <title>BugDays Are Back!</title>
      <link>http://www.mozillazine.org/talkback.html?article=2151</link>
    </item>

    <item>
      <title>Independent Status Reports</title>
      <link>http://www.mozillazine.org/talkback.html?article=2150</link>
    </item>

  </channel>

</rss>

We want to process all the item elements from each weblog.

for Example

<xsl:template match="weblogs">
  <xsl:apply-templates select="
    for $url in log/changesUrl
    return document($url)/item
  "/>
</xsl:template>

Conditional Expressions

Not all weblogs have a changesUrl

<xsl:template match="log">
  <xsl:apply-templates select="
    if (changesUrl)
     then document(changesUrl)
     else document(url)"/>
</xsl:template>

Quantified Expressions

<xsl:template match="weblogs">
  <xsl:if test="some $log in log satisfies changesURL">
     ????
  </xsl:if>
</xsl:template>

<xsl:template match="weblogs">
  <xsl:if test="every $log in log satisfies url">
    ????
  </xsl:if>
</xsl:template>

XSLT 2.0

XSLT 2.0 Goals

XSLT 2.0 Non-goals

XSLT 2.0 Requirements

Identifying 2.0 stylesheets

<xsl:stylesheet version="2.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <!-- Top level elements -->

</xsl:stylesheet>

No result tree fragments

xsl:for-each-group

Grouping example: input

Grouping example: desired output

<?xml version="1.0"?>
<forwardslash>

<section>
  <title>developers</title>
<story>
<title>ROX Desktop Update</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/180240</url>
<time>2002-02-18 18:50:13</time>
<author>timothy</author>
<department>small-simple-swift</department>
<topic>104</topic>
<comments>32</comments>
<image>topicx.jpg</image>
</story>

</section>

<section>
  <title>articles</title>

<story>
<title>HP Selling Systems With Linux</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/1712241</url>
<time>2002-02-18 17:37:20</time>
<author>timothy</author>
<department>wish-this-wasn't-remarkable</department>
<topic>173</topic>
<comments>188</comments>
<image>topichp.gif</image>
</story>

<story>
<title>Excellent Hacks to the ReplayTV 4000</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/1619213</url>
<time>2002-02-18 16:46:04</time>
<author>CmdrTaco</author>
<department>hardware-I-lust-after</department>
<topic>129</topic>
<comments>117</comments>
<image>topictv.jpg</image>
</story>

<story>
<title>Peek-a-Boo(ty)</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/1546226</url>
<time>2002-02-18 15:58:06</time>
<author>Hemos</author>
<department>pirate-treasure</department>
<topic>158</topic>
<comments>207</comments>
<image>topicprivacy.gif</image>
</story>

<story>
<title>Self-Shredding E-Mail</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/1343202</url>
<time>2002-02-18 14:37:45</time>
<author>timothy</author>
<department>plausible-deniability</department>
<topic>158</topic>
<comments>170</comments>
<image>topicprivacy.gif</image>
</story>

<story>
<title>CIA &amp;amp; KGB Gadgets On Display</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/0252219</url>
<time>2002-02-18 13:52:04</time>
<author>Hemos</author>
<department>looking-a-tthe-gear</department>
<topic>126</topic>
<comments>103</comments>
<image>topictech2.gif</image>
</story>


<story>
<title>How to Fix the Unix Configuration Nightmare</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/0248248</url>
<time>2002-02-18 10:48:36</time>
<author>Hemos</author>
<department>fixing-the-problem</department>
<topic>130</topic>
<comments>367</comments>
<image>topicunix.jpg</image>
</story>


</section>
<section>
  <title>science</title>


<story>
<title>Re-Building the Wright Flyer</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/060257</url>
<time>2002-02-18 12:29:12</time>
<author>timothy</author>
<department>we-hope-they-wear-modern-helmets</department>
<topic>126</topic>
<comments>132</comments>
<image>topictech2.gif</image>
</story>


<story>
<title>Sleep Less, Live Longer</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/0511253</url>
<time>2002-02-18 07:38:15</time>
<author>timothy</author>
<department>if-you're-reading-this</department>
<topic>134</topic>
<comments>309</comments>
<section>science</section>
<image>topicscience.gif</image>
</story>

<story>
<title>Warming and Slowing the World</title>
<url>http://slashdot.org/article.pl?sid=02/02/18/0243253</url>
<time>2002-02-18 04:39:39</time>
<author>Hemos</author>
<department>slowing-things-down</department>
<topic>134</topic>
<comments>312</comments>
<section>science</section>
<image>topicscience.gif</image>
</story>

</section>

</forwardslash>

Grouping example: stylesheet

<?xml version="1.0"?> 
<xsl:stylesheet version="2.0" 
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:template match="/">
    <forwardslash>
      <xsl:apply-templates select="*"/>
    </forwardslash>
  </xsl:template>

  <xsl:template match="backslash">
    <xsl:for-each-group select="story" group-by="section">
      <section>
        <title><xsl:value-of select="current-group()/section"/></title>
        <xsl:apply-templates select="."/>
      </section>
    </xsl:for-each-group>
  </xsl:template>

  <xsl:template match="story">
    <story>
      <xsl:apply-templates/>
    </story>
  </xsl:template>

  <xsl:template match="*">
    <xsl:copy-of select="."/>
  </xsl:template>

  <xsl:template match="section"/>

</xsl:stylesheet>

xsl:result-document

xsl:result-document Example

     <xsl:output name="ccl:html" method="html" encoding="ISO-8859-1" />

     <xsl:result-document href="index.html" format="ccl:html">
       <html>
         <head>
           <title><xsl:value-of select="title"/></title>         
         </head>
         <body> 
           <h1 align="center"><xsl:value-of select="title"/></h1> 
           <ul>
             <xsl:for-each select="slide">
               <li><a href="{format-number(position(),'00')}.html"><xsl:value-of select="title"/></a></li>
             </xsl:for-each>    
           </ul>           
           
           <p><a href="{translate(title,' ', '_')}.html">Entire Presentation as Single File</a></p>
              
           <hr/>
           <div align="center">
             <A HREF="01.html">Start</A> | <A HREF="/xml/">Cafe con Leche</A>
           </div>
           <hr/>
           <font size="-1">
              Copyright 2002 
              <a href="http://www.elharo.com/">Elliotte Rusty Harold</a><br/>       
              <a href="mailto:elharo@metalab.unc.edu">elharo@metalab.unc.edu</a><br/>
              Last Modified <xsl:apply-templates select="last_modified" mode="lm"/>
           </font>
         </body>     
       </html>     
     </xsl:result-document>

Sorting

<xsl:sort-key
  name = "Qualified Name">
  <!-- Content: (xsl:sort+) -->
</xsl:sort-key>

xsl:namespace

<xsl:namespace name="xsd">http://www.w3.org/2001/XMLSchema</xsl:namespace>

Value of a sequence

<x><xsl:value-of select="(1,2,3,4)" separator=" | "/></x>

<x>1 | 2 | 3 | 4</x>

default-xpath-namespace

An XSLT 1.0 stylesheet for working with XHTML

<?xml version="1.0"?>
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns="http://www.w3.org/1999/xhtml" 
  xmlns:html="http://www.w3.org/1999/xhtml" 
>

  <xsl:output method="html" encoding="ISO-8859-1"/>

  <xsl:template match="week">
    <html xml:lang="en" lang="en">
      <head><title><xsl:value-of select="//html:h1[1]"/></title></head>
      <body bgcolor="#ffffff" text="#000000">

        <xsl:apply-templates select="html:body"/>

        <font size="-1">Last Modified Mon June 5, 2001<br />
          Copyright 2001 Elliotte Rusty Harold<br />
          <a href="mailto:elharo@metalab.unc.edu">elharo@metalab.unc.edu</a>
        </font>
      </body>
    </html>
  </xsl:template>

  <xsl:template match="html:body">
    <xsl:apply-templates 
      select="text()[count(following-sibling::html:hr)>1]|*[count(following-sibling::html:hr)>1]" />

    <hr/>
  </xsl:template>

  <xsl:template match="html:*">
    <xsl:copy>
      <xsl:for-each select="@*">
        <xsl:copy-of select="."/>
      </xsl:for-each>
      <xsl:apply-templates/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="html:font[@size='-1']"></xsl:template>

  <xsl:template match="html:a">
    <xsl:apply-templates/>
  </xsl:template>

  <xsl:template match="html:applet">
    <xsl:apply-templates/>
  </xsl:template>

  <xsl:template match="html:param"/>

</xsl:stylesheet>

An XSLT 2.0 stylesheet for working with XHTML

<?xml version="1.0"?>
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns="http://www.w3.org/1999/xhtml" 
  default-xpath-namespace="http://www.w3.org/1999/xhtml"
>

  <xsl:output method="html" encoding="ISO-8859-1"/>

  <xsl:template match="week">
    <html xml:lang="en" lang="en">
      <head><title><xsl:value-of select="//h1[1]"/></title></head>
      <body bgcolor="#ffffff" text="#000000">

        <xsl:apply-templates select="body"/>

        <font size="-1">Last Modified Mon June 5, 2001<br />
          Copyright 2001 Elliotte Rusty Harold<br />
          <a href="mailto:elharo@metalab.unc.edu">elharo@metalab.unc.edu</a>
        </font>
      </body>
    </html>
  </xsl:template>

  <xsl:template match="body">
    <xsl:apply-templates 
     select="text()[count(following-sibling::hr)>1]|*[count(following-sibling::hr)>1]"/>

    <hr/>
  </xsl:template>

  <xsl:template match="*">
    <xsl:copy>
      <xsl:for-each select="@*">
        <xsl:copy-of select="."/>
      </xsl:for-each>
      <xsl:apply-templates/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="font[@size='-1']"></xsl:template>

  <xsl:template match="a">
    <xsl:apply-templates/>
  </xsl:template>

  <xsl:template match="applet">
    <xsl:apply-templates/>
  </xsl:template>

  <xsl:template match="param"/>

</xsl:stylesheet>

User defined data elements

Typed variables and parameters

Functions defined in XSLT

<xsl:function name="math:factorial"
 xmlns:math="http://www.example.com/math"
 exclude-result-prefixes="math">
  <xsl:param name="index" type="xsd:nonNegativeInteger"/>
  <xsl:result type="xsd:positiveInteger"
    select="if ($index eq 0) then 1
            else $index * math:factorial(index - 1)/>
</xsl:function>

Not parsing text files

XQuery

Three parts:

XQuery Language

Documents to Query

Physical Representations to Query

Where is XQuery used?

The XML Model vs. the Relational Model

A relational database contains tables An XML database contains collections
A relational table contains records with the same schema A collection contains XML documents with the same DTD
A relational record is an unordered list of named values An XML document is a tree of nodes
A SQL query returns an unordered set of records An XQuery returns an ordered sequence of nodes

Query Data Types

An example document to query

Most of the examples in this talk query this bibliography document at the (relative) URL bib.xml: 

<bib>
  <book year="1994">
  <title>TCP/IP Illustrated</title>
  <author><last>Stevens</last><first>W.</first></author>
  <publisher>Addison-Wesley</publisher>
  <price>65.95</price>
</book>

<book year="1992">
  <title>Advanced Programming in the Unix Environment</title>
  <author><last>Stevens</last><first>W.</first></author>
  <publisher>Addison-Wesley</publisher>
  <price>65.95</price>
</book>

<book year="2000">
  <title>Data on the Web</title>
  <author><last>Abiteboul</last><first>Serge</first></author>
  <author><last>Buneman</last><first>Peter</first></author>
  <author><last>Suciu</last><first>Dan</first></author>
  <publisher>Morgan Kaufmann Publishers</publisher>
  <price>39.95</price>
</book>

<book year="1999">
  <title>The Economics of Technology and Content for Digital TV</title>
  <editor>
    <last>Gerbarg</last><first>Darcy</first>
    <affiliation>CITI</affiliation>
  </editor>
  <publisher>Kluwer Academic Publishers</publisher>
  <price>129.95</price>
</book>

</bib>

Adapted from Mary Fernandez, Jerome Simeon, and Phil Wadler: XML Query Languages: Experiences and Exemplars, 1999, as adapted in XML Query Use Cases

The XQuery FLWOR

photo of flower

Query: List titles of all books

   for $t in document("bib.xml")/bib/book/title
   return
      $t

Adapted from XML Query Use Cases

Query Result: Book Titles

  <title>TCP/IP Illustrated</title>
  <title>Advanced Programming in the Unix Environment</title>
  <title>Data on the Web</title>
  <title>The Economics of Technology and Content for Digital TV</title>

Adapted from XML Query Use Cases

XQueryX

Element Constructors

List titles of all books in a bib element. Put each title in a book element. 

<bib>
  {
   for $t in document("bib.xml")/bib/book/title
   return
    <book>
     { $t }
    </book>
  }
</bib>

Adapted from XML Query Use Cases

Query Result: Book Titles

<bib>
  <book>
    <title>TCP/IP Illustrated</title>
  </book>
  <book>
    <title>Advanced Programming in the Unix Environment</title>
  </book>
  <book>
    <title>Data on the Web</title>
  </book>
  <book>
    <title>The Economics of Technology and Content for Digital TV</title>
  </book>
</bib>

Adapted from XML Query Use Cases

Query with where

Adapted from XML Query Use Cases

Query Result: Titles of books published by Addison-Wesley

<bib>
    <title>TCP/IP Illustrated</title>
    <title>Advanced Programming in the Unix Environment</title>
</bib>

Adapted from XML Query Use Cases

Query with Booleans

Adapted from XML Query Use Cases

Query Result: books published by Addison-Wesley after 1993

<bib>
    <title>Advanced Programming in the Unix Environment</title>
</bib>

Adapted from XML Query Use Cases

Attribute Constructors

Adapted from XML Query Use Cases

Query Result: books published by Addison-Wesley after 1993, including their year and title.

<bib>
  <book year="1992">
    <title>Advanced Programming in the Unix Environment</title>
  </book>
</bib>

Adapted from XML Query Use Cases

Query with multiple variables

Create a list of all the title-author pairs, with each pair enclosed in a result element.

<results>
 {
   for $b in document("bib.xml")/bib/book,
     $t in $b/title,
     $a in $b/author
   return
    <result>
    { $t }
    { $a }
    </result>
  }
</results>

Adapted from XML Query Use Cases

Query Result: A list of all the title-author pairs

<results>
    <result>
         <title>TCP/IP Illustrated</title>
         <author><last>Stevens</last><first>W.</first></author>
    </result>
    <result>
         <title>Advanced Programming in the Unix Environment</title>
         <author><last>Stevens</last><first>W.</first></author>
    </result>
    <result>
         <title>Data on the Web</title>
         <author><last>Abiteboul</last><first>Serge</first></author>
    </result>
    <result>
         <title> Data on the Web</title>
         <author><last>Buneman</last><first>Peter</first></author>
    </result>
    <result>
         <title>Data on the Web</title>
         <author><last>Suciu</last><first>Dan</first></author>
    </result>
</results>

Adapted from XML Query Use Cases

Nested Queries

For each book in the bibliography, list the title and authors, grouped inside a result element.

<results>
 {
   for $b in document("bib.xml")/bib/book
   return
    <result>
     { $b/title }
     {  
       for $a in $b/author
       return $a
     }
    </result>
 }
</results>

Adapted from XML Query Use Cases

Query Result: A list of the title and authors of each book in the bibliography

<?xml version="1.0"?>
<results xmlns:ino="http://namespaces.softwareag.com/tamino/response2" xmlns:xql="http://metalab.unc.edu/xql/">
  <result>
    <title>TCP/IP Illustrated</title>
    <author>
      <last>Stevens</last>
      <first>W.</first>
    </author>
  </result>
  <result>
    <title>Advanced Programming in the Unix Environment</title>
    <author>
      <last>Stevens</last>
      <first>W.</first>
    </author>
  </result>
  <result>
    <title>Data on the Web</title>
    <author>
      <last>Abiteboul</last>
      <first>Serge</first>
    </author>
    <author>
      <last>Buneman</last>
      <first>Peter</first>
    </author>
    <author>
      <last>Suciu</last>
      <first>Dan</first>
    </author>
  </result>
  <result>
    <title>The Economics of Technology and Content for Digital TV</title>
  </result>
</results>

Adapted from XML Query Use Cases

Query with distinct

For each author in the bibliography, list the author's name and the titles of all books by that author, grouped inside a result element.

<results>
 {
   for $a in distinct-values(document("bib.xml")//author)
   return
    <result>
     { $a }
     {  for $b in document("bib.xml")/bib/book[author=$a]
        return $b/title
     }
    </result>
 }
</results>

Adapted from XML Query Use Cases

Query Result

<results>
  <result>
    <author><last>Stevens</last><first>W.</first></author>
    <title>TCP/IP Illustrated</title>
    <title>Advanced Programming in the Unix Environment</title>
  </result>

  <result>
    <author><last>Abiteboul</last><first>Serge</first></author>
    <title>Data on the Web</title>
  </result>

  <result>
    <author><last>Buneman</last><first>Peter</first></author>
    <title>Data on the Web</title>
  </result>

  <result>
    <author><last>Suciu</last><first>Dan</first></author>
      <title>Data on the Web</title>
  </result>
</results>

Adapted from XML Query Use Cases

Query with sorting

List the titles and years of all books published by Addison-Wesley after 1991, in alphabetic order.

<bib>
 {
   for $b in document("bib.xml")//book
    [publisher = "Addison-Wesley" and @year > "1991"]
   order by (title)
   return
    <book>
     { $b/@year } { $b/title }
    </book> 
 }
</bib>

June 2002 version of QuiP does not yet handle this one.

Adapted from XML Query Use Cases

Query Result

<bib>
  <book year="1992">
    <title>Advanced Programming in the Unix Environment</title>
  </book>
  <book year="1994">
    <title>TCP/IP Illustrated</title>
   </book>
</bib>

Adapted from XML Query Use Cases

Queries with functions

Adapted from XML Query Use Cases

Query Result

<result>
 <book>
  <title> Data on the Web </title>
  <author> <last>Suciu</last> <first>Dan</first> </author>
 </book>
</result>

Adapted from XML Query Use Cases

A different document about books

Sample data at "reviews.xml":

<reviews>
  <entry>
    <title>Data on the Web</title>
    <price>34.95</price>
    <review>
       A very good discussion of semi-structured database
       systems and XML.
    </review>
  </entry>
  <entry>
    <title>Advanced Programming in the Unix Environment</title>
    <price>65.95</price>
    <review>
      A clear and detailed discussion of UNIX programming.
    </review>
  </entry>
  <entry>
    <title>TCP/IP Illustrated</title>
    <price>65.95</price>
    <review>
      One of the best books on TCP/IP.
    </review>
  </entry>
</reviews>

Adapted from XML Query Use Cases

This document uses a different DTD

<!ELEMENT reviews (entry*)>
<!ELEMENT entry   (title, price, review)>
<!ELEMENT title   (#PCDATA)>
<!ELEMENT price   (#PCDATA)>
<!ELEMENT review  (#PCDATA)>

Query that joins two documents

For each book found in both bib.xml and reviews.xml, list the title of the book and its price from each source.

<books-with-prices>
 {
   for $b in document("bib.xml")//book,
     $a in document("reviews.xml")//entry
   where $b/title = $a/title
   return
    <book-with-prices>
     { $b/title },
       <price-amazon> { $a/price/text() } </price-amazon>
       <price-bn> { $b/price/text() } </price-bn>
    </book-with-prices>
 }
</books-with-prices>

Adapted from XML Query Use Cases

Result 

<books-with-prices>
  <book-with-prices>
    <title>TCP/IP Illustrated</title>
    <price-amazon>65.95</price-amazon>
    <price-bn>65.95</price-bn>
  </book-with-prices>

  <book-with-prices>
    <title>Advanced Programming in the Unix Environment</title>
    <price-amazon>65.95</price-amazon>
    <price-bn>65.95</price-bn>
  </book-with-prices>

  <book-with-prices>
    <title>Data on the Web</title>
    <price-amazon>34.95</price-amazon>
    <price-bn>39.95</price-bn>
  </book-with-prices>
</books-with-prices>

Adapted from XML Query Use Cases

prices.xml Query Sample Data

The next query also uses an input document named "prices.xml": 

<prices>
  <book>
    <title>Advanced Programming in the Unix Environment</title>
    <source>www.amazon.com</source>
    <price>65.95</price>
  </book>
  <book>
    <title>Advanced Programming in the Unix Environment</title>
    <source>www.bn.com</source>
    <price>65.95</price>
  </book>
  <book>
    <title>TCP/IP Illustrated</title>
    <source>www.amazon.com</source>
    <price>65.95</price>
  </book>
  <book>
    <title>TCP/IP Illustrated</title>
    <source>www.bn.com</source>
    <price>65.95</price>
  </book>
  <book>
    <title>Data on the Web</title>
    <source>www.amazon.com</source>
    <price>34.95</price>
  </book>
  <book>
    <title>Data on the Web</title>
    <source>www.bn.com</source>
    <price>39.95</price>
  </book>
</prices>

Adapted from XML Query Use Cases

Query with reused variables

<results>
 {
   let $doc := document("prices.xml")
   for $t in distinct-values($doc/prices/book/title)
   let $p := $doc/prices/book[title = $t]/price
   return
    <minprice title = "{ $t }" >
     { min($p) }
    </minprice>
 }
</results>

Adapted from XML Query Use Cases

Query Result

<results>
  <minprice title="Advanced Programming in the Unix Environment"> 65.95 </minprice>
  <minprice title="TCP/IP Illustrated"> 65.95 </minprice>
  <minprice title="Data on the Web"> 34.95 </minprice>
</results>

Adapted from XML Query Use Cases

Multiple FLWR Queries

<bib>
 {
   for $b in document("bib.xml")//book[author]
   return
    <book>
     { $b/title }
     { $b/author }
    </book>,
   for $b in document("bib.xml")//book[editor]
   return
    <reference>
     { $b/title }
     <org> { $b/editor/affiliation/text() } </org>
    </reference>
 }
</bib>

Adapted from XML Query Use Cases

Query Result

<bib>
    <book>
         <title>TCP/IP Illustrated</title>
         <author><last> Stevens </last> <first> W.</first></author>
    </book>

    <book>
         <title>Advanced Programming in the Unix Environment</title>
         <author><last>Stevens</last><first>W.</first></author>
    </book>

    <book>
         <title>Data on the Web</title>
         <author><last>Abiteboul</last><first>Serge</first></author>
         <author><last>Buneman</last><first>Peter</first></author>
         <author><last>Suciu</last><first>Dan</first></author>
    </book>

    <reference>
        <title>The Economics of Technology and Content for Digital TV</title>
        <org>CITI</org>
    </reference>
</bib>

Adapted from XML Query Use Cases

Query Software

What's the difference between XQuery and XSLT?

To Learn More

Index | Cafe con Leche
Copyright 2002, 2003 Elliotte Rusty Harold
elharo@metalab.unc.edu
Last Modified March 19, 2003