XML Query Use Cases

<!ELEMENT bib  (book* )>
<!ELEMENT book  (title,  (author+ | editor+ ), publisher, price )>
<!ATTLIST book  year CDATA  #REQUIRED >
<!ELEMENT author  (last, first )>
<!ELEMENT editor  (last, first, affiliation )>
<!ELEMENT title  (#PCDATA )>
<!ELEMENT last  (#PCDATA )>
<!ELEMENT first  (#PCDATA )>
<!ELEMENT affiliation  (#PCDATA )>
<!ELEMENT publisher  (#PCDATA )>
<!ELEMENT price  (#PCDATA )>

<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>

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

<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>

<!ELEMENT chapter (title, section*)>
<!ELEMENT section (title, section*)>
<!ELEMENT title (#PCDATA)>

<chapter>
    <title>Data Model</title>
    <section>
        <title>Syntax For Data Model</title>
    </section>
    <section>
        <title>XML</title>
        <section>
            <title>Basic Syntax</title>
        </section>
        <section>
            <title>XML and Semistructured Data</title>
        </section>
    </section>
</chapter>

<!ELEMENT prices (book*)>
<!ELEMENT book (title, source, price)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT source (#PCDATA)>
<!ELEMENT price (#PCDATA)>

<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>

<bib>
 {
  for $b in document("http://www.bn.com/bib.xml")/bib/book
  where $b/publisher = "Addison-Wesley" and $b/@year > 1991
  return
    <book year="{ $b/@year }">
     { $b/title }
    </book>
 }
</bib>

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

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

<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>

<results>
{
    for $b in document("http://www.bn.com/bib.xml")/bib/book
    return
        <result>
            { $b/title }
            { $b/author  }
        </result>
}
</results>

<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>
        <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>

<results>
  {
    for $a in distinct-values(document("http://www.bn.com/bib.xml")//author)
    return
        <result>
            { $a }
            {
                for $b in document("http://www.bn.com/bib.xml")/bib/book
                where some $ba in $b/author satisfies deep-equal($ba,$a)
                return $b/title
            }
        </result>
  }
</results>

<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>

<books-with-prices>
  {
    for $b in document("http://www.bn.com/bib.xml")//book,
        $a in document("http://www.amazon.com/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>

<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>

<bib>
  {
    for $b in document("http://www.bn.com/bib.xml")//book
    where count($b/author) > 0
    return
        <book>
            { $b/title }
            {
                for $a in $b/author[position()<=2] 
                return $a
            }
            {
                if (count($b/author) > 2)
                then <et-al/>
                else ()
            }
        </book>
  }
</bib>

<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>
        <et-al/>
    </book>
</bib>

<bib>
  {
    for $b in document("http://www.bn.com/bib.xml")//book
    where $b/publisher = "Addison-Wesley" and $b/@year > 1991
    return
        <book>
            { $b/@year }
            { $b/title }
        </book>
    sort by (title)
  }
</bib>

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

for $b in document("http://www.bn.com/bib.xml")//book
let $e := $b/*[contains(string(.), "Suciu")
               and ends-with(local-name(.), "or")]
where exists($e)
return
    <book>
        { $b/title }
        { $e }
    </book>

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

<results>
  {
    for $t in document("books.xml")//(chapter | section)/title
    where contains($t/text(), "XML")
    return $t
  }
</results>

<results>
    <title>XML</title>
    <title>XML and Semistructured Data</title>
</results>

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

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

<bib>
{
        for $b in document("http://www.bn.com/bib.xml")//book[author]
        return
            <book>
                { $b/title }
                { $b/author }
            </book>
}
{
        for $b in document("http://www.bn.com/bib.xml")//book[editor]
        return
          <reference>
            { $b/title }
            {$b/editor/affiliation}
          </reference>
}
</bib> 

<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>
        <affiliation>CITI</affiliation>
    </reference>
</bib>

<bib>
{
    for $book1 in document("http://www.bn.com/bib.xml")//book,
        $book2 in document("http://www.bn.com/bib.xml")//book
    let $aut1 := for $a in $book1/author
order by $a/last, $a/first
return $a
    let $aut2 := for $a in $book2/author
order by $a/last, $a/first
return $a
    where $book1 << $book2
    and not($book1/title = $book2/title)
    and sequence-deep-equal($aut1, $aut2)
    return
        <book-pair>
            { $book1/title }
            { $book2/title }
        </book-pair>
}
</bib>

<bib>
    <book-pair>
        <title>TCP/IP Illustrated</title>
        <title>Advanced Programming in the Unix environment</title>
    </book-pair>
</bib>

<!DOCTYPE book [
  <!ELEMENT book (title, author+, section+)>
  <!ELEMENT title (#PCDATA)>
  <!ELEMENT author (#PCDATA)>
  <!ELEMENT section (title, (p | figure | section)* )>
  <!ATTLIST section
      id         ID    #IMPLIED
      difficulty CDATA #IMPLIED>
  <!ELEMENT p (#PCDATA)>
  <!ELEMENT figure (title, image)>
  <!ATTLIST figure
       width   CDATA   #REQUIRED
       height  CDATA   #REQUIRED >
  <!ELEMENT image EMPTY>
  <!ATTLIST image
       source  CDATA   #REQUIRED >
]>

<?xml version="1.0"?>
<!DOCTYPE book SYSTEM "book.dtd">
<book>
  <title>Data on the Web</title>
  <author>Serge Abiteboul</author>
  <author>Peter Buneman</author>
  <author>Dan Suciu</author>
  <section id="intro" difficulty="easy" >
    <title>Introduction</title>
    <p>Text ... </p>
    <section>
      <title>Audience</title>
      <p>Text ... </p>
    </section>
    <section>
      <title>Web Data and the Two Cultures</title>
      <p>Text ... </p>
      <figure height="400" width="400">
        <title>Traditional client/server architecture</title>
        <image source="csarch.gif"/>
      </figure>
      <p>Text ... </p>
    </section>
  </section>
  <section id="syntax" difficulty="medium" >
    <title>A Syntax For Data</title>
    <p>Text ... </p>
    <figure height="200" width="500">
      <title>Graph representations of structures</title>
      <image source="graphs.gif"/>
    </figure>
    <p>Text ... </p>
    <section>
      <title>Base Types</title>
      <p>Text ... </p>
    </section>
    <section>
      <title>Representing Relational Databases</title>
      <p>Text ... </p>
      <figure height="250" width="400">
        <title>Examples of Relations</title>
        <image source="relations.gif"/>
      </figure>
    </section>
    <section>
      <title>Representing Object Databases</title>
      <p>Text ... </p>
    </section>      
  </section>
</book>

define function toc( element $e )
  returns element*
{
  let $n := local-name( $e )
  return
    if ($n = "section")
    then
        <section>
           { $e/@* }
           { toc($e/*) }
        </section>
    else if ($n = "title")
    then $e
    else ()
}
<toc>
  {
    toc( document("book1.xml")/book )
  }
</toc>

<toc>
    <section id="intro" difficulty="easy">
        <title>Introduction</title>
        <section>
            <title>Audience</title>
        </section>
        <section>
            <title>Web Data and the Two Cultures</title>
        </section>
    </section>
    <section id="syntax" difficulty="medium">
        <title>A Syntax For Data</title>
        <section>
            <title>Base Types</title>
        </section>
        <section>
            <title>Representing Relational Databases</title>
        </section>
        <section>
            <title>Representing Object Databases</title>
        </section>
    </section>
</toc>

<figlist>
  {
    for $f in document("book1.xml")//figure
    return
        <figure>
            { $f/@* }
            { $f/title }
        </figure>
  }
</figlist>

<figlist>
    <figure  height="400" width="400">
        <title>Traditional client/server architecture</title>
    </figure>
    <figure  height="200" width="500">
        <title>Graph representations of structures</title>
    </figure>
    <figure  height="250" width ="400">
        <title>Examples of Relations</title>
    </figure>
</figlist>

<section_count>{ count(document("book.xml")//section) }</section_count>,
<figure_count>{ count(document("book.xml")//figure) }</figure_count>

<section_count>7</section_count>
<figure_count>3</figure_count>

<top_section_count>
 {
   count(document("book.xml")/book/section)
 }
</top_section_count>

<top_section_count>2</top_section_count>

<section_list>
  {
    for $s in document("book.xml")//section
    let $f := $s/figure
    return
        <section title="{ $s/title/text() }" figcount="{ count($f) }"/>
  }
</section_list>

<section_list>
    <section title="Introduction" figcount="0"/>
    <section title="Audience" figcount="0"/>
    <section title="Web Data and the Two Cultures" figcount="1"/>
    <section title="A Syntax For Data" figcount="1"/>
    <section title="Base Types" figcount="0"/>
    <section title="Representing Relational Databases" figcount="1"/>
    <section title="Representing Object Databases" figcount="0"/>
</section_list>

define function section_summary($s as element) as element
{
    <section>
        { $s/@* }
        { $s/title }
        <figcount>{ count($s/figure) }</figcount>
        {
            for $ss in $s/section
            return section_summary($ss)
        }
    </section>
}
<toc>
  {
    for $s in document("book.xml")/book/section
    return section_summary($s)
  }
</toc>

<toc>
    <section id="intro" difficulty="easy">
        <title>Introduction</title>
        <figcount>0</figcount>
        <section>
            <title>Audience</title>
            <figcount>0</figcount>
        </section>
        <section>
            <title>Web Data and the Two Cultures</title>
            <figcount>1</figcount>
        </section>
    </section>
    <section id="syntax" difficulty="medium">
        <title>A Syntax For Data</title>
        <figcount>1</figcount>
        <section>
            <title>Base Types</title>
            <figcount>0</figcount>
        </section>
        <section>
            <title>Representing Relational Databases</title>
            <figcount>1</figcount>
        </section>
        <section>
            <title>Representing Object Databases</title>
            <figcount>0</figcount>
        </section>
    </section>
</toc>

<!DOCTYPE report [
  <!ELEMENT report (section*)>
  <!ELEMENT section (section.title, section.content)>
  <!ELEMENT section.title  (#PCDATA )>
  <!ELEMENT section.content  (#PCDATA | anesthesia | prep
                            | incision | action | observation )*>
  <!ELEMENT anesthesia (#PCDATA)>
  <!ELEMENT prep ( (#PCDATA | action)* )>
  <!ELEMENT incision ( (#PCDATA | geography | instrument)* )>
  <!ELEMENT action ( (#PCDATA | instrument )* )>
  <!ELEMENT observation (#PCDATA)>
  <!ELEMENT geography (#PCDATA)>
  <!ELEMENT instrument (#PCDATA)>
]>

<report>
  <section>
    <section.title>Procedure</section.title>
     <section.content>
      The patient was taken to the operating room where she was placed
      in supine position and
      <anesthesia>induced under general anesthesia.</anesthesia>
      <prep>
        <action>A Foley catheter was placed to decompress the bladder</action>
        and the abdomen was then prepped and draped in sterile fashion.
      </prep> 
      <incision>
        A curvilinear incision was made
        <geography>in the midline immediately infraumbilical</geography>
        and the subcutaneous tissue was divided
        <instrument>using electrocautery.</instrument>
      </incision>
      The fascia was identified and
      <action>#2 0 Maxon stay sutures were placed on each side of the midline.
      </action>
      <incision>
        The fascia was divided using
        <instrument>electrocautery</instrument>
        and the peritoneum was entered.
      </incision>
      <observation>The small bowel was identified.</observation>
      and
      <action>
        the
        <instrument>Hasson trocar</instrument>
        was placed under direct visualization.
      </action>
      <action>
        The
        <instrument>trocar</instrument>
        was secured to the fascia using the stay sutures.
      </action>
     </section.content>
  </section>
</report>

for $s in document("report1.xml")//section[section.title = "Procedure"]
return ($s//incision)[2]/instrument

<instrument>electrocautery</instrument>

for $s in document("report1.xml")//section[section.title = "Procedure"]
return ($s//instrument)[position()<=2]

<instrument>using electrocautery.</instrument>
<instrument>electrocautery</instrument>

let $i2 := (document("report1.xml")//incision)[2]
for $a in (document("report1.xml")//action)[. >> $i2][position()<=2]
return $a//instrument

<instrument>Hasson trocar</instrument>
<instrument>trocar</instrument>

for $p in document("report1.xml")//section[section.title = "Procedure"]
where not(some $a in $p//anesthesia satisfies
        $a << ($p//incision)[1] )
return $p

define function precedes($a as node, $b as node) as boolean
{
    $a << $b
      and
    empty($a//node() intersect $b)
}
define function follows($a as node, $b as node) as boolean
{
    $a >> $b
      and
    empty($b//node() intersect $a)
}
<critical_sequence>
 {
  let $proc := document("report1.xml")//section[section.title="Procedure"][1]
  for $n in $proc//node()
  where follows($n, ($proc//incision)[1])
    and precedes($n, ($proc//incision)[2])
  return $n
 }
</critical_sequence>

<critical_sequence>
 {
  let $proc := document("report1.xml")//section[section.title="Procedure"][1],
      $i1 :=  ($proc//incision)[1],
      $i2 :=  ($proc//incision)[2]
  for $n in $proc//node() except $i1//node()
  where $n >> $i1 and $n << $i2
  return $n
 }
</critical_sequence>

<critical_sequence>
      The fascia was identified and
      <action>#2 0 Maxon stay sutures were placed on each side of the midline.</action>#2 0 Maxon stay sutures were placed on each side of the midline.
</critical_sequence>

USERS ( USERID, NAME, RATING )
ITEMS ( ITEMNO, DESCRIPTION, OFFERED_BY, START_DATE, END_DATE, RESERVE_PRICE )
BIDS ( USERID, ITEMNO, BID, BID_DATE )

<!DOCTYPE users [
  <!ELEMENT users   (user_tuple*)>
  <!ELEMENT user_tuple (userid, name, rating?)>
  <!ELEMENT userid  (#PCDATA)>
  <!ELEMENT name    (#PCDATA)>
  <!ELEMENT rating  (#PCDATA)>
]>
<!DOCTYPE items [
  <!ELEMENT items       (item_tuple*)>
  <!ELEMENT item_tuple  (itemno, description, offered_by,
                              start_date?, end_date?, reserve_price? )>
  <!ELEMENT itemno      (#PCDATA)>
  <!ELEMENT description (#PCDATA)>
  <!ELEMENT offered_by  (#PCDATA)>
  <!ELEMENT start_date  (#PCDATA)>
  <!ELEMENT end_date    (#PCDATA)>
  <!ELEMENT reserve_price (#PCDATA)>
]>
<!DOCTYPE bids [
  <!ELEMENT bids      (bid_tuple*)>
  <!ELEMENT bid_tuple (userid, itemno, bid, bid_date)>
  <!ELEMENT userid    (#PCDATA)>
  <!ELEMENT itemno    (#PCDATA)>
  <!ELEMENT bid       (#PCDATA)>
  <!ELEMENT bid_date  (#PCDATA)>
]>

<items>
  <item_tuple>
    <itemno>1001</itemno>
    <description>Red Bicycle</description>
    <offered_by>U01</offered_by>
    <start_date>1999-01-05</start_date>
    <end_date>1999-01-20</end_date>
    <reserve_price>40</reserve_price>
  </item_tuple>
  <!-- !!! Snip !!! -->
<users>
  <user_tuple>
    <userid>U01</userid>
    <name>Tom Jones</name>
    <rating>B</rating>
  </user_tuple>
  <!-- !!! Snip !!! -->
<bids>
  <bid_tuple>
    <userid>U02</userid>
    <itemno>1001</itemno>
    <bid>35</bid>
    <bid_date>1999-01-07</bid_date>
    </bid_tuple>
  <bid_tuple>
  <!-- !!! Snip !!! -->

<result>
  {
    for $i in document("items.xml")//item_tuple
    where $i/start_date <= current-date()
      and $i/end_date >= current-date()
      and contains($i/description, "Bicycle")
    order by $1/itemno
return
        <item_tuple>
            { $i/itemno }
            { $i/description }
        </item_tuple>
  }
</result>

<result>
    <item_tuple>
        <itemno>1003</itemno>
        <description>Old Bicycle</description>
    </item_tuple>
    <item_tuple>
        <itemno>1007</itemno>
        <description>Racing Bicycle</description>
    </item_tuple>
</result>

<result>
  {
    for $i in document("items.xml")//item_tuple
    let $b := document("bids.xml")//bid_tuple[itemno = $i/itemno]
    where contains($i/description, "Bicycle")
    order by $1/itemno
return
        <item_tuple>
            { $i/itemno }
            { $i/description }
            <high_bid>{ max(for $z in $b/bid return decimal($z)) }</high_bid>
        </item_tuple>
  }
</result>

<result>
<item_tuple>
<itemno>1001</itemno>
            <description>Red Bicycle</description>
            <high_bid>55.0</high_bid>
</item_tuple><item_tuple>
<itemno>1003</itemno>
            <description>Old Bicycle</description>
            <high_bid>20.0</high_bid>
</item_tuple><item_tuple>
<itemno>1007</itemno>
            <description>Racing Bicycle</description>
            <high_bid>225.0</high_bid>
</item_tuple><item_tuple>
<itemno>1008</itemno>
            <description>Broken Bicycle</description>
            <high_bid></high_bid>
</item_tuple>
</result>

<result>
  {
    for $u in document("users.xml")//user_tuple
    for $i in document("items.xml")//item_tuple
    where $u/rating > "C"
       and $i/reserve_price > 1000
       and $i/offered_by = $u/userid
    return
        <warning>
            { $u/name }
            { $u/rating }
            { $i/description }
            { $i/reserve_price }
        </warning>
  }
</result>

<result>
    <warning>
        <name>Dee Linquent</name>
        <rating>D</rating>
        <description>Helicopter</description>
        <reserve_price>50000</reserve_price>
    </warning>
</result>

<result>
  {
    for $i in document("items.xml")//item_tuple
    where empty(document("bids.xml")//bid_tuple[itemno = $i/itemno])
    return
        <no_bid_item>
            { $i/itemno }
            { $i/description }
        </no_bid_item>
  }
</result>

<result>
    <no_bid_item>
        <itemno>1005</itemno>
        <description>Tennis Racket</description>
    </no_bid_item>
    <no_bid_item>
        <itemno>1006</itemno>
        <description>Helicopter</description>
    </no_bid_item>
    <no_bid_item>
        <itemno>1008</itemno>
        <description>Broken Bicycle</description>
    </no_bid_item>
</result>

<result>
  {
    for $seller in document("users.xml")//user_tuple,
        $buyer in  document("users.xml")//user_tuple,
        $item in  document("items.xml")//item_tuple,
        $highbid in  document("bids.xml")//bid_tuple
    where $seller/name = "Tom Jones"
      and $seller/userid  = $item/offered_by
      and contains($item/description , "Bicycle")
      and $item/itemno  = $highbid/itemno
      and $highbid/userid  = $buyer/userid
      and $highbid/bid = max(
                             for $x in document("bids.xml")//bid_tuple
                                  [itemno = $item/itemno]/bid
                             return decimal($x)
                         )
    order by ($item/itemno)
return
        <jones_bike>
            { $item/itemno }
            { $item/description }
            <high_bid>{ $highbid/bid }</high_bid>
            <high_bidder>{ $buyer/name }</high_bidder>
        </jones_bike>
  }
</result>

<result>
  {
    for $seller in unordered document("users.xml")//user_tuple,
        $buyer in  unordered document("users.xml")//user_tuple,
        $item in  unordered document("items.xml")//item_tuple,
        $highbid in  document("bids.xml")//bid_tuple
    where $seller/name = "Tom Jones"
      and $seller/userid  = $item/offered_by
      and contains($item/description , "Bicycle")
      and $item/itemno  = $highbid/itemno
      and $highbid/userid  = $buyer/userid
      and $highbid/bid = max(for $x in unordered document("bids.xml")//bid_tuple
                                [itemno = $item/itemno]/bid
                             return decimal(data($x)))
    order by $item/itemno
return
        <jones_bike>
            { $item/itemno }
            { $item/description }
            <high_bid>{ $highbid/bid }</high_bid>
            <high_bidder>{ $buyer/name }</high_bidder>
        </jones_bike>
  }
</result>

<result>
    <jones_bike>
        <itemno>1001</itemno>
        <description>Red Bicycle</description>
        <high_bid>
            <bid>55</bid>
        </high_bid>
        <high_bidder>
            <name>Mary Doe</name>
        </high_bidder>
    </jones_bike>
</result>

<result>
  {
    for $item in document("items.xml")//item_tuple
    let $b := document("bids.xml")//bid_tuple[itemno = $item/itemno]
    let $z := max(for $x in $b/bid return decimal($x))
    where $item/reserve_price * 2 < $z
    return
        <successful_item>
            { $item/itemno }
            { $item/description }
            { $item/reserve_price }
            <high_bid>{$z }</high_bid>
         </successful_item>
  }
</result>

<result>
    <successful_item>
        <itemno>1002</itemno>
        <description>Motorcycle</description>
        <reserve_price>500</reserve_price>
        <high_bid>1200.0</high_bid>
    </successful_item>
    <successful_item>
        <itemno>1004</itemno>
        <description>Tricycle</description>
        <reserve_price>15</reserve_price>
        <high_bid>40.0</high_bid>
    </successful_item>
</result>

let $allbikes := document("items.xml")//item_tuple
                    [contains(description, "Bicycle")
                     or contains(description, "Tricycle")]
let $bikebids := document("bids.xml")//bid_tuple[itemno = $allbikes/itemno]
return
    <high_bid>
      {
        max(for $x in $bikebids/bid return decimal($x))
      }
    </high_bid>

<high_bid>225.0</high_bid>

let $item := document("items.xml")//item_tuple
  [end_date >= date("1999-03-01") and end_date <= date("1999-03-31")]
return
    <item_count>
      {
        count($item)
      }
    </item_count>

<item_count>3</item_count>

<result>
  {
    let $end_dates := document("items.xml")//item_tuple/end_date
    for $m in distinct-values(for $e in $end_dates
                              return get-month-from-date($e))
    let $item := document("items.xml")
        //item_tuple[get-year-from-date(end_date) = 1999
                     and get-month-from-date(end_date) = $m]
    order by $m
return
        <monthly_result>
            <month>{ $m }</month>
            <item_count>{ count($item) }</item_count>
        </monthly_result>
  }
</result>

<result>
    <monthly_result>
        <month>01</month>
        <item_count>1</item_count>
    </monthly_result>
    <monthly_result>
        <month>02</month>
        <item_count>2</item_count>
    </monthly_result>
    <monthly_result>
        <month>03</month>
        <item_count>3</item_count>
    </monthly_result>
    <monthly_result>
        <month>04</month>
        <item_count>1</item_count>
    </monthly_result>
    <monthly_result>
        <month>05</month>
        <item_count>1</item_count>
    </monthly_result>
</result>

<result>
 {
    for $highbid in document("bids.xml")//bid_tuple,
        $user in document("users.xml")//user_tuple
    where $user/userid = $highbid/userid
      and $highbid/bid = max(for $x in document("bids.xml")//bid_tuple
                              [itemno=$highbid/itemno]/bid return decimal($x))
    order by $highbid/itemno
return
        <high_bid>
            { $highbid/itemno }
            { $highbid/bid }
            <bidder>{ $user/name/text() }</bidder>
        </high_bid>
 }
</result>

<result>
    <high_bid>
        <itemno>1001</itemno>
        <bid>55</bid>
        <bidder>Mary Doe</bidder>
    </high_bid>
    <high_bid>
        <itemno>1002</itemno>
        <bid>1200</bid>
        <bidder>Mary Doe</bidder>
    </high_bid>
    <high_bid>
        <itemno>1003</itemno>
        <bid>20</bid>
        <bidder>Jack Sprat</bidder>
    </high_bid>
    <high_bid>
        <itemno>1004</itemno>
        <bid>40</bid>
        <bidder>Tom Jones</bidder>
    </high_bid>
    <high_bid>
        <itemno>1007</itemno>
        <bid>225</bid>
        <bidder>Roger Smith</bidder>
    </high_bid>
</result>

let $highbid := max(for $x in document("bids.xml")//bid_tuple/bid
                    return decimal($x))
return
    <result>
     {
        for $item in document("items.xml")//item_tuple,
            $b in document("bids.xml")//bid_tuple[itemno = $item/itemno]
        where $b/bid = $highbid
        return
            <expensive_item>
                { $item/itemno }
                { $item/description }
                <high_bid>{ $highbid }</high_bid>
            </expensive_item>
     }
    </result>

<result>
    <expensive_item>
        <itemno>1002</itemno>
        <description>Motorcycle</description>
        <high_bid>1200.0</high_bid>
    </expensive_item>
</result>

define function bid_summary ()
{
    for $i in distinct-values(document("bids.xml")//itemno)
    let $b := document("bids.xml")//bid_tuple[itemno = $i]
    return
        <bid_count>
            { $i }
            <nbids>{ count($b) }</nbids>
        </bid_count>
}
<result>
 {
    let $bid_counts := bid_summary(),
        $maxbids := max(for $x in $bid_counts/nbids return decimal($x)),
        $maxitemnos := $bid_counts[nbids = $maxbids]
    for $item in document("items.xml")//item_tuple,
        $bc in $bid_counts
    where $bc/nbids =  $maxbids and $item/itemno = $bc/itemno
    return
        <popular_item>
            { $item/itemno }
            { $item/description }
            <bid_count>{ $bc/nbids/text() }</bid_count>
        </popular_item>
 }
</result>

<result>
    <popular_item>
        <itemno>1001</itemno>
        <description>Red Bicycle</description>
        <bid_count>5</bid_count>
    </popular_item>
    <popular_item>
        <itemno>1002</itemno>
        <description>Motorcycle</description>
        <bid_count>5</bid_count>
    </popular_item>
</result>

<result>
 {
    for $uid in distinct-values(document("bids.xml")//userid),
        $u in document("users.xml")//user_tuple[userid = $uid]
    let $b := document("bids.xml")//bid_tuple[userid = $uid]
    order by $u/userid
return
        <bidder>
            { $u/userid }
            { $u/name }
            <bidcount>{ count($b) }</bidcount>
            <avgbid>{ avg(for $x in $b/bid return decimal($x)) }</avgbid>
        </bidder>
  }
</result>

<result>
    <bidder>
        <userid>U01</userid>
        <name>Tom Jones</name>
        <bidcount>2</bidcount>
        <avgbid>220.0</avgbid>
    </bidder>
    <bidder>
        <userid>U02</userid>
        <name>Mary Doe</name>
        <bidcount>5</bidcount>
        <avgbid>387.0</avgbid>
    </bidder>
    <bidder>
        <userid>U03</userid>
        <name>Dee Linquent</name>
        <bidcount>2</bidcount>
        <avgbid>487.5</avgbid>
    </bidder>
    <bidder>
        <userid>U04</userid>
        <name>Roger Smith</name>
        <bidcount>5</bidcount>
        <avgbid>266.0</avgbid>
    </bidder>
    <bidder>
        <userid>U05</userid>
        <name>Jack Sprat</name>
        <bidcount>2</bidcount>
        <avgbid>110.0</avgbid>
    </bidder>
</result>

<result>
 {
    for $i in distinct-values(document("bids.xml")//itemno)
    let $b := document("bids.xml")//bid_tuple[itemno = $i]
    let $avgbid := decimal(avg(for $x in $s/bid return decimal($x)))
where count($b) >= 3
    order by $avgbid descending
return
        <popular_item>
            { $i }
            <avgbid>{ $avgbid }</avgbid>
        </popular_item>
  }
</result>

<result>
    <popular_item>
        <itemno>1002</itemno>
        <avgbid>800.0</avgbid>
    </popular_item>
    <popular_item>
        <itemno>1007</itemno>
        <avgbid>200.0</avgbid>
    </popular_item>
    <popular_item>
        <itemno>1001</itemno>
        <avgbid>45.0</avgbid>
    </popular_item>
</result>

<result>
  {
    for $u in document("users.xml")//user_tuple
    let $b := document("bids.xml")//bid_tuple[userid=$u/userid and bid>=100]
    where count($b) > 1
    return
        <big_spender>{ $u/name/text() }</big_spender>
  }
</result>

<result>
    <big_spender>Mary Doe</big_spender>
    <big_spender>Dee Linquent</big_spender>
    <big_spender>Roger Smith</big_spender>
</result>

<result>
  {
    for $u in document("users.xml")//user_tuple
    let $b := document("bids.xml")//bid_tuple[userid = $u/userid]
    order by $u/userid
return
        <user>
            { $u/userid }
            { $u/name }
            {
                if (empty($b))
                then <status>inactive</status>
                else <status>active</status>
            }
        </user>
  }
</result>

<result>
    <user>
        <userid>U01</userid>
        <name>Tom Jones</name>
        <status>active</status>
    </user>
    <user>
        <userid>U02</userid>
        <name>Mary Doe</name>
        <status>active</status>
    </user>
    <user>
        <userid>U03</userid>
        <name>Dee Linquent</name>
        <status>active</status>
    </user>
    <user>
        <userid>U04</userid>
        <name>Roger Smith</name>
        <status>active</status>
    </user>
    <user>
        <userid>U05</userid>
        <name>Jack Sprat</name>
        <status>active</status>
    </user>
    <user>
        <userid>U06</userid>
        <name>Rip Van Winkle</name>
        <status>inactive</status>
    </user>
</result>

<frequent_bidder>
  {
    for $u in document("users.xml")//user_tuple
    where
      every $item in document("items.xml")//item_tuple satisfies
        some $b in document("bids.xml")//bid_tuple satisfies
          ($item/itemno = $b/itemno and $u/userid = $b/userid)
    return
        $u/name
  }
</frequent_bidder>

<result>
  {
    for $u in document("users.xml")//user_tuple
    return
        <user>
            { $u/name }
            {
                for $b in distinct-values(document("bids.xml")//bid_tuple
                                             [userid = $u/userid]/itemno),
                for $i in document("items.xml")//item_tuple[itemno = $b]
                let $descr := $i/description/text()
order by $descr
return
                    <bid_on_item>{ $descr }</bid_on_item>
            }
        </user>
  }
</result>

<result>
    <user>
        <name>Dee Linquent</name>
        <bid_on_item>Motorcycle</bid_on_item>
        <bid_on_item>Racing Bicycle</bid_on_item>
    </user>
    <user>
        <name>Jack Sprat</name>
        <bid_on_item>Old Bicycle</bid_on_item>
        <bid_on_item>Racing Bicycle</bid_on_item>
    </user>
    <user>
        <name>Mary Doe</name>
        <bid_on_item>Motorcycle</bid_on_item>
        <bid_on_item>Red Bicycle</bid_on_item>
    </user>
    <user>
        <name>Rip Van Winkle</name>
    </user>
    <user>
        <name>Roger Smith</name>
        <bid_on_item>Motorcycle</bid_on_item>
        <bid_on_item>Old Bicycle</bid_on_item>
        <bid_on_item>Racing Bicycle</bid_on_item>
        <bid_on_item>Red Bicycle</bid_on_item>
    </user>
    <user>
        <name>Tom Jones</name>
        <bid_on_item>Motorcycle</bid_on_item>
        <bid_on_item>Tricycle</bid_on_item>
    </user>
</result>

 <!NOTATION cgm PUBLIC "Computer Graphics Metafile">
 <!NOTATION ccitt PUBLIC "CCITT group 4 raster">
 <!ENTITY % text "(#PCDATA | emph)*">
 <!ENTITY infoflow SYSTEM "infoflow.ccitt" NDATA ccitt>
 <!ENTITY tagexamp SYSTEM "tagexamp.cgm"   NDATA cgm>
 <!ELEMENT report (title, chapter+)>
 <!ELEMENT title %text;>
 <!ELEMENT chapter (title, intro?, section*)>
 <!ATTLIST chapter
               shorttitle CDATA #IMPLIED>
 <!ELEMENT intro (para | graphic)+>
 <!ELEMENT section (title, intro?, topic*)>
 <!ATTLIST section
               shorttitle CDATA #IMPLIED
               sectid ID #IMPLIED>
 <!ELEMENT topic (title, (para | graphic)+)>
 <!ATTLIST topic
               shorttitle CDATA #IMPLIED
               topicid ID #IMPLIED>
 <!ELEMENT para (#PCDATA | emph | xref)*>
 <!ATTLIST para
               security (u | c | s | ts) "u">
 <!ELEMENT emph %text;>
 <!ELEMENT graphic EMPTY>
 <!ATTLIST graphic
               graphname ENTITY #REQUIRED>
 <!ELEMENT xref EMPTY>
 <!ATTLIST xref
               xrefid IDREF #IMPLIED>

 0: <!DOCTYPE report SYSTEM "report.dtd">
 1: <report>
 2: <title>Getting started with SGML</title>
 3: <chapter>
 4: <title>The business challenge</title>
 5: <intro>
 6: <para>With the ever-changing and growing global market, companies and
 7: large organizations are searching for ways to become more viable and
 8: competitive. Downsizing and other cost-cutting measures demand more
 9: efficient use of corporate resources. One very important resource is
10: an organization's information.</para>
11: <para>As part of the move toward integrated information management,
12: whole industries are developing and implementing standards for
13: exchanging technical information. This report describes how one such
14: standard, the Standard Generalized Markup Language (SGML), works as
15: part of an overall information management strategy.</para>
16: <graphic graphname="infoflow"/></intro></chapter>
17: <chapter>
18: <title>Getting to know SGML</title>
19: <intro>
20: <para>While SGML is a fairly recent technology, the use of
21: <emph>markup</emph> in computer-generated documents has existed for a
22: while.</para></intro>
23: <section shorttitle="What is markup?">
24: <title>What is markup, or everything you always wanted to know about
25: document preparation but were afraid to ask?</title>
26: <intro>
27: <para>Markup is everything in a document that is not content. The
28: traditional meaning of markup is the manual <emph>marking</emph> up
29: of typewritten text to give instructions for a typesetter or
30: compositor about how to fit the text on a page and what typefaces to
31: use. This kind of markup is known as <emph>procedural markup</emph>.</para></intro>
32: <topic topicid="top1">
33: <title>Procedural markup</title>
34: <para>Most electronic publishing systems today use some form of
35: procedural markup. Procedural markup codes are good for one
36: presentation of the information.</para></topic>
37: <topic topicid="top2">
38: <title>Generic markup</title>
39: <para>Generic markup (also known as descriptive markup) describes the
40: <emph>purpose</emph> of the text in a document. A basic concept of
41: generic markup is that the content of a document must be separate from
42: the style. Generic markup allows for multiple presentations of the
43: information.</para></topic>
44: <topic topicid="top3">
45: <title>Drawbacks of procedural markup</title>
46: <para>Industries involved in technical documentation increasingly
47: prefer generic over procedural markup schemes. When a company changes
48: software or hardware systems, enormous data translation tasks arise,
49: often resulting in errors.</para></topic></section>
50: <section shorttitle="What is SGML?">
51: <title>What <emph>is</emph> SGML in the grand scheme of the universe, anyway?</title>
52: <intro>
53: <para>SGML defines a strict markup scheme with a syntax for defining
54: document data elements and an overall framework for marking up
55: documents.</para>
56: <para>SGML can describe and create documents that are not dependent on
57: any hardware, software, formatter, or operating system. Since SGML documents
58: conform to an international standard, they are portable.</para></intro></section>
59: <section shorttitle="How does SGML work?">
60: <title>How is SGML and would you recommend it to your grandmother?</title>
61: <intro>
62: <para>You can break a typical document into three layers: structure,
63: content, and style. SGML works by separating these three aspects and
64: deals mainly with the relationship between structure and content.</para></intro>
65: <topic topicid="top4">
66: <title>Structure</title>
67: <para>At the heart of an SGML application is a file called the DTD, or
68: Document Type Definition. The DTD sets up the structure of a document,
69: much like a database schema describes the types of information it
70: handles.</para>
71: <para>A database schema also defines the relationships between the
72: various types of data. Similarly, a DTD specifies <emph>rules</emph>
73: to help ensure documents have a consistent, logical structure.</para></topic>
74: <topic topicid="top5">
75: <title>Content</title>
76: <para>Content is the information itself. The method for identifying
77: the information and its meaning within this framework is called
78: <emph>tagging</emph>. Tagging must
79: conform to the rules established in the DTD (see <xref xrefid="top4"/>).</para>
80: <graphic graphname="tagexamp"/></topic>
81: <topic topicid="top6">
82: <title>Style</title>
83: <para>SGML does not standardize style or other processing methods for
84: information stored in SGML.</para></topic></section></chapter>
85: <chapter>
86: <title>Resources</title>
87: <section>
88: <title>Conferences, tutorials, and training</title>
89: <intro>
90: <para>The Graphic Communications Association has been
91: instrumental in the development of SGML. GCA provides conferences,
92: tutorials, newsletters, and publication sales for both members and
93: non-members.</para>
94: <para security="c">Exiled members of the former Soviet Union's secret
95: police, the KGB, have infiltrated the upper ranks of the GCA and are
96: planning the Final Revolution as soon as DSSSL is completed.</para>
97: </intro>
98: </section>
99: </chapter>
100:</report>

<result>
  {
    input()//report//para
  }
</result>

<result>
  {
    input()//intro/para
  }
</result>

<result>
  {
    for $c in input()//chapter
    where empty($c/intro)
    return $c/section/intro/para
  }
</result>

<result>
  {
    (((input()//chapter)[2]//section)[3]//para)[2]
  }
</result>

<result>
  {
    input()//para[@security = "c"]
  }
</result>

<result>
  {
    for $s in input()//section/@shorttitle
    return <stitle>{ $s }</stitle>
  }
</result>

<result>
  {
    for $i in input()//intro/para[1]
    return
        <first_letter>{ substring(string($i), 1, 1) }</first_letter>
  }
</result>

<result>
  {
    input()//section[contains(string(.//title), "is SGML")]
  }
</result>

<result>
  {
    input()//section[contains(.//title/text(), "is SGML")]
  }
</result>

<result>
  {
    for $id in input()//xref/@xrefid
    return input()//topic[@topicid = $id]
  }
</result>

<result>
  {
    let $x := input()//xref[@xrefid = "top4"],
        $t := input()//title[. << $x]
    return $t[last()]
  }
</result>

<!ELEMENT company (name, ticker_symbol?, description?,
          business_code, partners?, competitors?)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT ticker_symbol (#PCDATA)>
<!ELEMENT description (#PCDATA)>
<!ELEMENT business_code (#PCDATA)>
<!ELEMENT partners (partner+)>
<!ELEMENT partner (#PCDATA)>
<!ELEMENT competitors (competitor+)>
<!ELEMENT competitor (#PCDATA)>

<!ELEMENT news (news_item*)>
<!ELEMENT news_item (title, content, date, author?, news_agent)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT content (par | figure)+ >
<!ELEMENT date (#PCDATA)>
<!ELEMENT author (#PCDATA)>
<!ELEMENT news_agent (#PCDATA)>
<!ELEMENT par (#PCDATA | quote | footnote)*>
<!ELEMENT quote (#PCDATA)>
<!ELEMENT footnote (#PCDATA)>
<!ELEMENT figure (title, image)>
<!ELEMENT image EMPTY>
<!ATTLIST image
    source  CDATA  #REQUIRED >

<?xml version="1.0" encoding="ISO-8859-1"?>
<news>
<news_item>
   <title> Gorilla Corporation acquires YouNameItWeIntegrateIt.com </title>
   <content>
      <par> Today, Gorilla Corporation announced that it will purchase
          YouNameItWeIntegrateIt.com. The shares of
          YouNameItWeIntegrateIt.com dropped $3.00 as a result of this
          announcement.
      </par>
      <par> As a result of this acquisition, the CEO of
          YouNameItWeIntegrateIt.com Bill Smarts resigned. He did not
          announce what he will do next.  Sources close to
          YouNameItWeIntegrateIt.com hint that Bill Smarts might be
          taking a position in Foobar Corporation.
      </par>
      <par>YouNameItWeIntegrateIt.com is a leading systems integrator
          that enables <quote>brick and mortar</quote> companies to
          have a presence on the web.
      </par>
   </content>
   <date>1-20-2000</date>
   <author>Mark Davis</author>
   <news_agent>News Online</news_agent>
</news_item>
<news_item>
   <title>Foobar Corporation releases its new line of Foo products
   today</title>
   <content>
      <par> Foobar Corporation releases the 20.9 version of its Foo
            products.  The new version of Foo products solve known
            performance problems which existed in 20.8 line and
            increases the speed of Foo based products tenfold. It also
            allows wireless clients to be connected to the Foobar
            servers.
      </par>
      <par> The President of Foobar Corporation announced that they
            were proud to release 20.9 version of Foo products and
            they will upgrade existing customers <footnote>where
            service agreements exist</footnote>
            promptly. TheAppCompany Inc. immediately announced that it
            will release the new version of its products to utilize
            the 20.9 architecture within the next three months.
      </par>
      <figure>
          <title>Presidents of Foobar Corporation and TheAppCompany
          Inc. Shake Hands</title> <image source="handshake.jpg"/>
      </figure>
   </content>
   <date>1-20-2000</date>
   <news_agent>Foobar Corporation</news_agent>
</news_item>
<news_item> <title>Foobar Corporation is suing Gorilla Corporation for
   patent infringement </title>
   <content>
      <par> In surprising developments today, Foobar Corporation
         announced that it is suing Gorilla Corporation for patent
         infringement. The patents that were mentioned as part of the
         lawsuit are considered to be the basis of Foobar
         Corporation's <quote>Wireless Foo</quote> line of products.
      </par>
      <par>The tension between Foobar and Gorilla Corporations has
         been increasing ever since the Gorilla Corporation acquired
         more than 40 engineers who have left Foobar Corporation,
         TheAppCompany Inc. and YouNameItWeIntegrateIt.com over the
         past 3 months. The engineers who have left the Foobar
         corporation and its partners were rumored to be working on
         the next generation of server products and applications which
         will directly compete with Foobar's Foo 20.9 servers. Most of
         the engineers have relocated to Hawaii where the Gorilla
         Corporation's server development is located.
      </par>
   </content>
   <date>1-20-2000</date>
   <news_agent>Reliable News Corporation</news_agent>
</news_item>
</news>

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE company SYSTEM "company.dtd">
<company>
   <name>Foobar Corporation</name>
   <ticker_symbol>FOO</ticker_symbol>
   <description>Foobar Corporation is a maker of Foo(TM) and
        Foobar(TM) products and a leading software company with a 300
        Billion dollar revenue in 1999. It is located in Alaska.
   </description>
   <business_code>Software</business_code>
   <partners>
        <partner>YouNameItWeIntegrateIt.com</partner>
        <partner>TheAppCompany Inc.</partner>
   </partners>
   <competitors>
        <competitor>Gorilla Corporation</competitor>
   </competitors>
</company>

input()//news_item/title[contains(./text(), "Foobar Corporation")]

<title>Foobar Corporation releases its new line of Foo
products today</title>
<title>Foobar Corporation is suing Gorilla Corporation for patent
infringement </title>

define function partners($company as xs:string) as element*
{
    let $c := document("company-data.xml")//company[name = $company]
    return $c//partner
}
let $foobar_partners := partners("Foobar Corporation")
for $item in input()//news_item
where
  some $t in $item//title satisfies
    (contains($t/text(), "Foobar Corporation")
    and some $partner in $foobar_partners satisfies
      contains($t/text(), $partner/text()))
  or some $par in $item//par satisfies
   (contains(string($par), "Foobar Corporation")
     and some $partner in $foobar_partners satisfies
        contains(string($par), $partner/text()))
return
    <news_item>
        { $item/title }
        { $item/date }
    </news_item>

<news_item>
    <title> Gorilla Corporation acquires YouNameItWeIntegrateIt.com </title>
    <date>1-20-2000</date>
</news_item>
<news_item>
    <title>Foobar Corporation releases its new line of Foo products today</title>
    <date>1-20-2000</date>
</news_item>
<news_item>
    <title>Foobar Corporation is suing Gorilla Corporation for patent
    infringement </title>
    <date>1-20-2000</date>
</news_item>

define function partners($company as xs:string) as element*
{
    let $c := document("company-data.xml")//company[name = $company]
    return $c//partner
}
for $item in input()//news_item,
    $c in document("company-data.xml")//company
let $partners := partners($c/name)
where contains(string($item), $c/name)
  and some $p in $partners satisfies
    contains(string($item), $p) and $item/news_agent != $c/name
return
    $item

for $item in input()//news_item
where contains(string($item/content), "Gorilla Corporation")
return
    <item_summary>
        { $item/title/text() }.
        { $item/date/text() }.
        { string(($item//par)[1]) }
    </item_summary>

<item_summary>
   Gorilla Corporation acquires YouNameItWeIntegrateIt.com. 1-20-2000.
   Today, Gorilla Corporation announced that it will purchase
   YouNameItWeIntegrateIt.com. The shares of YouNameItWeIntegrateIt.com
   dropped $3.00 as a result of this announcement.
</item_summary>
<item_summary>
   Foobar Corporation is suing Gorilla Corporation for patent infringement.
   1-20-2000. In surprising developments today, Foobar Corporation announced
   that it is suing Gorilla Corporation for patent infringement. The patents
   that were mentioned as part of the lawsuit are considered to be the
   basis of Foobar Corporation's <quote>Wireless Foo</quote> line of products.
</item_summary>

<?xml version="1.0" encoding="ISO-8859-1"?>
<ma:AuctionWatchList
    xmlns:ma="http://www.example.com/AuctionWatch"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:anyzone="http://www.example.com/auctioneers#anyzone"
    xmlns:eachbay="http://www.example.com/auctioneers#eachbay"
    xmlns:yabadoo="http://www.example.com/auctioneers#yabadoo"
>
<!-- ________________________________________________________________________________ -->
<ma:Auction anyzone:ID="0321K372910">
    <ma:AuctionHomepage
        xlink:type="simple"
        xlink:href="http://www.example.com/item/0321K372910"
    />
    <ma:Schedule>
        <ma:Open    xmlns:dt="http://www.w3.org/2001/XMLSchema"
                dt:type="timeInstant">2000-03-21:07:41:34-05:00</ma:Open>
        <ma:Close    xmlns:dt="http://www.w3.org/2001/XMLSchema"
                dt:type="timeInstant">2000-03-23:07:41:34-05:00</ma:Close>
    </ma:Schedule>
    <ma:Price>
        <ma:Start ma:currency="USD">3.00</ma:Start>
        <ma:Current ma:currency="USD">10.00</ma:Current>
        <ma:Number_of_Bids>5</ma:Number_of_Bids>
    </ma:Price>
    <ma:Trading_Partners>
        <ma:High_Bidder>
            <eachbay:ID>RecordsRUs</eachbay:ID>
            <eachbay:PositiveComments>231</eachbay:PositiveComments>
            <eachbay:NeutralComments>2</eachbay:NeutralComments>
            <eachbay:NegativeComments>5</eachbay:NegativeComments>
            <ma:MemberInfoPage
                xlink:type="simple"
                xlink:href="http://auction.eachbay.com/members?get=RecordsRUs"
                xlink:role="ma:MemberInfoPage"
            />           
        </ma:High_Bidder>
        <ma:Seller>
            <anyzone:ID>VintageRecordFreak</anyzone:ID>
            <anyzone:Member_Since>October 1999</anyzone:Member_Since>
            <anyzone:Rating>5</anyzone:Rating>
            <ma:MemberInfoPage
               xlink:type="simple"
               xlink:href="http://auction.anyzone.com/members/VintageRecordFreak"
               xlink:role="ma:MemberInfoPage"
            />
        </ma:Seller>
    </ma:Trading_Partners>
    <ma:Details>
        <record xmlns="http://www.example.org/music/records">
            <artist>Miles Davis</artist>
            <title>In a Silent Way</title>
            <recorded>1969</recorded>
            <label>Columbia Records</label>
            <remark>
                With Miles Davis (trumpet), Herbie Hancock (Electric
                Piano), Chick Corea (Electric Piano), Wayne Shorter
                (Tenor Sax), Josef Zawinul (Electric Piano &amp;
                Organ), John McLaughlin (Guitar), and Tony Williams
                (Drums).  The liner notes were written by Frank Glenn,
                and the record is in fine condition.
            </remark>
        </record>
    </ma:Details>
</ma:Auction>
<!-- ________________________________________________________________________________ -->
<ma:Auction yabadoo:ID="13143816">
    <ma:AuctionHomepage
        xlink:type="simple"
        xlink:href="http://auctions.yabadoo.com/auction/13143816"
    />
    <ma:Schedule>
        <ma:Open    xmlns:dt="http://www.w3.org/2001/XMLSchema"
                dt:type="timeInstant">2000-03-19:17:03:00-04:00</ma:Open>
        <ma:Close    xmlns:dt="http://www.w3.org/2001/XMLSchema"
                dt:type="timeInstant">2000-03-29:17:03:00-04:00</ma:Close>
    </ma:Schedule>
    <ma:Price>
        <ma:Start ma:currency="USD">3.00</ma:Start>
        <ma:Current ma:currency="USD">3.00</ma:Current>
        <ma:Number_of_Bids>0</ma:Number_of_Bids>
    </ma:Price>
    <ma:Trading_Partners>
        <ma:High_Bidder>
            <eachbay:ID>VintageRecordFreak</eachbay:ID>
            <eachbay:PositiveComments>232</eachbay:PositiveComments>
            <eachbay:NeutralComments>0</eachbay:NeutralComments>
            <eachbay:NegativeComments>0</eachbay:NegativeComments>
            <ma:MemberInfoPage
                xlink:type="simple"
                xlink:href="http://auction.eachbay.com/showRating/user=VintageRecordFreak"
                xlink:role="ma:MemberInfoPage"
            />           
        </ma:High_Bidder>
        <ma:Seller xmlns:seller="http://www.example.com/auctioneers#eachbay">
            <seller:ID>StarsOn45</seller:ID>
            <seller:PositiveComments>80</seller:PositiveComments>
            <seller:NeutralComments>1</seller:NeutralComments>
            <seller:NegativeComments>2</seller:NegativeComments>
            <ma:MemberInfoPage
                xlink:type="simple"
                xlink:href="http://auction.eachbay.com/showRating/user=StarsOn45"
                xlink:role="ma:MemberInfoPage"
            />           
        </ma:Seller>
    </ma:Trading_Partners>
    <ma:Details>
        <record xmlns="http://www.example.org/music/records">
            <artist>Wynton Marsalis</artist>
            <title>Think of One ...</title>
            <recorded>1983</recorded>
            <label>Columbia Records</label>
            <remark xml:lang="en"> Columbia Records 12" 33-1/3 rpm LP,
                #FC-38641, Stereo. The record is still clean and shiny
                and looks unplayed (looks like NM condition).  The
                cover has very light surface and edge wear.
            </remark>
            <remark xml:lang="de"> Columbia Records 12" 33-1/3 rpm LP,
                #FC-38641, Stereo. Die Platte ist noch immer sauber
                und gl舅zend und sieht ungespielt aus
                (NM Zustand). Das Cover hat leichte Abnutzungen an
                Oberfl臘he und Ecken.
            </remark>
        </record>
    </ma:Details>
</ma:Auction>        
</ma:AuctionWatchList>

<Q1>
  {
    for $n in distinct-values(
                  for $i in (input()//* | input()//@*)
                  return namespace-uri($i)
               )
    return  <ns>{$n}</ns>
  }
</Q1>

<Q1>
  </ns>http://www.example.com/AuctionWatch</ns>
  </ns>http://www.example.com/auctioneers#anyzone</ns>
  </ns>http://www.w3.org/1999/xlink</ns>
  </ns>http://www.w3.org/2001/XMLSchema</ns>
  </ns>http://www.example.com/auctioneers#eachbay</ns>
  </ns>http://www.example.org/music/records</ns>
  </ns>http://www.example.com/auctioneers#yabadoo</ns>
  </ns>xml</ns>
</Q1>

declare namespace music = "http://www.example.org/music/records"
<Q2>
  {
    input()//music:title
  }
</Q2>

<Q2 xmlns:music="http://www.example.org/music/records">
  <music:title>In a Silent Way</music:title>
  <music:title>Think of One ...</music:title>
</Q2>

declare namespace dt = "http://www.w3.org/2001/XMLSchema"
<Q3>
  {
    input()//*[@dt:*]
  }
</Q3>

<Q3 xmlns:dt="http://www.w3.org/2001/XMLSchema">
  <ma:Open xmlns:ma="http://www.example.com/AuctionWatch"
           dt:type="timeInstant">2000-03-21:07:41:34-05:00</ma:Open>
  <ma:Close xmlns:ma="http://www.example.com/AuctionWatch"
           dt:type="timeInstant">2000-03-23:07:41:34-05:00</ma:Close>
  <ma:Open xmlns:ma="http://www.example.com/AuctionWatch"
           dt:type="timeInstant">2000-03-19:17:03:00-04:00</ma:Open>
  <ma:Close xmlns:ma="http://www.example.com/AuctionWatch"
           dt:type="timeInstant">2000-03-29:17:03:00-04:00</ma:Close>
</Q3>

declare namespace xlink = "http://www.w3.org/1999/xlink"
<Q4>
  {
    for $hr in input()//@xlink:href
    return <ns>{ $hr }</ns>
  }
</Q4>

<Q4 xmlns:xlink="http://www.w3.org/1999/xlink">
  <ns xlink:href="http://www.example.com/item/0321K372910"/>
  <ns xlink:href="http://auction.eachbay.com/members?get=RecordsRUs"/>
  <ns xlink:href="http://auction.anyzone.com/members/VintageRecordFreak"/>
  <ns xlink:href="http://auctions.yabadoo.com/auction/13143816"/>
  <ns xlink:href="http://auction.eachbay.com/showRating/user=VintageRecordFreak"/>
  <ns xlink:href="http://auction.eachbay.com/showRating/user=StarsOn45"/>
</Q4>

declare namespace music = "http://www.example.org/music/records"
<Q5>
  {
     input()//music:record[music:remark/@xml:lang = "de"]
  }
</Q5>

<Q5 xmlns:music="http://www.example.org/music/records">
<music:record>
    <music:artist>Wynton Marsalis</music:artist>
    <music:title>Think of One ...</music:title>
    <music:recorded>1983</music:recorded>
    <music:label>Columbia Records</music:label>
    <music:remark xml:lang="en"> Columbia Records 12" 33-1/3 rpm LP,
        #FC-38641, Stereo. The record is still clean and shiny and
        looks unplayed (looks like NM condition).  The cover has very
        light surface and edge wear. 
    </music:remark>
    <music:remark xml:lang="de"> Columbia Records 12" 33-1/3 rpm LP,
        #FC-38641, Stereo. Die Platte ist noch immer sauber und
        gl舅zend und sieht ungespielt aus (NM Zustand). Das Cover hat
        leichte Abnutzungen an Oberfl臘he und Ecken. 
    </music:remark>
</music:record>
</Q5>

declare namespace ma = "http://www.example.com/AuctionWatch"
declare namespace anyzone = "http://www.example.com/auctioneers#anyzone"
<Q6>
  {
    input()//ma:Auction[@anyzone:ID]/ma:Schedule/ma:Close
  }
</Q6>

<Q6 xmlns:ma="http://www.example.com/AuctionWatch">
  <ma:Close xmlns:dt="http://www.w3.org/2001/XMLSchema" dt:type="timeInstant">2000-03-23:07:41:34-05:00</ma:Close>
</Q6> 

declare namespace ma = "http://www.example.com/AuctionWatch"
<Q7>
  {
    for $a in document("data/ns-data.xml")//ma:Auction
    let $seller_id := $a/ma:Trading_Partners/ma:Seller/*:ID,
        $buyer_id := $a/ma:Trading_Partners/ma:High_Bidder/*:ID
    where namespace-uri($seller_id) = namespace-uri($buyer_id)
    return
        $a/ma:AuctionHomepage
  }
</Q7>

<Q7 xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:ma="http://www.example.com/AuctionWatch" >
  <ma:AuctionHomepage xlink:type="simple"
                    xlink:href="http://auctions.yabadoo.com/auction/13143816" />
</Q7>

declare namespace ma = "http://www.example.com/AuctionWatch"
<Q8>
  {
    for $s in input()//ma:Trading_Partners/(ma:Seller | ma:High_Bidder)
    where $s/*:NegativeComments = 0
    return $s
  }
</Q8>

<Q8 xmlns:ma="http://www.example.com/AuctionWatch">
    <ma:High_Bidder xmlns:eachbay="http://www.example.com/auctioneers#eachbay"
                    xmlns:xlink="http://www.w3.org/1999/xlink">
        <eachbay:ID>VintageRecordFreak</eachbay:ID>
        <eachbay:PositiveComments>232</eachbay:PositiveComments>
        <eachbay:NeutralComments>0</eachbay:NeutralComments>
        <eachbay:NegativeComments>0</eachbay:NegativeComments>
        <ma:MemberInfoPage xlink:type="simple"
           xlink:href="http://auction.eachbay.com/showRating/user=VintageRecordFreak"
           xlink:role="ma:MemberInfoPage"/>
    </ma:High_Bidder>
</Q8>

<!DOCTYPE partlist [
    <!ELEMENT partlist (part*)>
    <!ELEMENT part EMPTY>
    <!ATTLIST part
          partid  CDATA  #REQUIRED
          partof  CDATA  #IMPLIED
          name    CDATA  #REQUIRED>
]>

<!DOCTYPE parttree [
    <!ELEMENT parttree (part*)>
    <!ELEMENT part (part*)>
    <!ATTLIST part
          partid  CDATA  #REQUIRED
          name    CDATA  #REQUIRED>
]>

<?xml version="1.0" encoding="ISO-8859-1"?>
<partlist>
  <part partid="0" name="car"/>
  <part partid="1" partof="0" name="engine"/>
  <part partid="2" partof="0" name="door"/>
  <part partid="3" partof="1" name="piston"/>
  <part partid="4" partof="2" name="window"/>
  <part partid="5" partof="2" name="lock"/>
  <part partid="10" name="skateboard"/>
  <part partid="11" partof="10" name="board"/>
  <part partid="12" partof="10" name="wheel"/>
  <part partid="20" name="canoe"/>
</partlist>

define function one_level ($p as element) as element
{
    <part partid="{ $p/@partid }"
          name="{ $p/@name }" >
        {
            for $s in document("partlist.xml")//part
            where $s/@partof = $p/@partid
            return one_level($s)
        }
    </part>
}
<parttree>
  {
    for $p in document("partlist.xml")//part[empty(@partof)]
    return one_level($p)
  }
</parttree>

<parttree>
    <part partid="0" name="car">
        <part partid="1" name="engine">
            <part partid="3" name="piston"/>
        </part>
        <part partid="2" name="door">
            <part partid="4" name="window"/>
            <part partid="5" name="lock"/>
        </part>
    </part>
    <part partid="10" name="skateboard">
        <part partid="11" name="board"/>
        <part partid="12" name="wheel"/>
    </part>
    <part partid="20" name="canoe"/>
</parttree>

<schema targetNamespace="http://www.example.com/IPO"
        xmlns="http://www.w3.org/2001/XMLSchema"
        xmlns:ipo="http://www.example.com/IPO">
 <annotation>
  <documentation xml:lang="en">
   International Purchase order schema for Example.com
   Copyright 2000 Example.com. All rights reserved.
  </documentation>
 </annotation>
 <!-- include address constructs -->
 <include
 schemaLocation="http://www.example.com/schemas/address.xsd"/>
 <element name="purchaseOrder" type="ipo:PurchaseOrderType"/>
 <element name="comment" type="string"/>
 <complexType name="PurchaseOrderType">
  <sequence>
   <element name="shipTo"     type="ipo:Address"/>
   <element name="billTo"     type="ipo:Address"/>
   <element ref="ipo:comment" minOccurs="0"/>
   <element name="items"      type="ipo:Items"/>
  </sequence>
  <attribute name="orderDate" type="date"/>
 </complexType>
 <complexType name="Items">
  <sequence>
   <element name="item" minOccurs="0" maxOccurs="unbounded">
    <complexType>
     <sequence>
      <element name="productName" type="string"/>
      <element name="quantity">
       <simpleType>
        <restriction base="positiveInteger">
         <maxExclusive value="100"/>
        </restriction>
       </simpleType>
      </element>
      <element name="USPrice"    type="decimal"/>
      <element ref="ipo:comment" minOccurs="0"/>
      <element name="shipDate"   type="date" minOccurs="0"/>
     </sequence>
     <attribute name="partNum" type="ipo:SKU" use="required"/>
    </complexType>
   </element>
  </sequence>
 </complexType>
 <simpleType name="SKU">
  <restriction base="string">
   <pattern value="\d{3}-[A-Z]{2}"/>
  </restriction>
 </simpleType>
</schema>

<schema targetNamespace="http://www.example.com/IPO"
        xmlns="http://www.w3.org/2001/XMLSchema"
        xmlns:ipo="http://www.example.com/IPO"
elementFormDefault="qualified">
 <annotation>
   <documentation xml:lang="en">
     Addresses for International Purchase order schema
     Copyright 2000 Example.com. All rights reserved.
   </documentation>
 </annotation>
 <complexType name="Address">
   <sequence>
     <element name="name" type="string"/>
     <element name="street" type="string"/>
     <element name="city" type="string"/>
   </sequence>
 </complexType>
 <complexType name="USAddress">
   <complexContent>
     <extension base="ipo:Address">
       <sequence>
         <element name="state" type="ipo:USState"/>
         <element name="zip" type="positiveInteger"/>
       </sequence>
     </extension>
   </complexContent>
 </complexType>
 <complexType name="UKAddress">
   <complexContent>
     <extension base="ipo:Address">
       <sequence>
         <element name="postcode" type="ipo:UKPostcode"/>
       </sequence>
       <attribute name="exportCode" type="positiveInteger" fixed="1"/>
     </extension>
   </complexContent>
 </complexType>
 <!-- other Address derivations for more countries -->
 <simpleType name="USState">
   <restriction base="string">
     <enumeration value="AK"/>
     <enumeration value="AL"/>
     <enumeration value="AR"/>
     <!-- and so on ... -->
     <enumeration value="PA"/>
   </restriction>
 </simpleType>
 <!-- simple type definition for UKPostcode -->
 <simpleType name="UKPostcode">
    <restriction base="string">
        <pattern value="[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][A-Z]{2}"/>
    </restriction>
 </simpleType>
</schema>   

<?xml version="1.0"?>
<ipo:purchaseOrder
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:ipo="http://www.example.com/IPO"
  orderDate="1999-12-01">
    <shipTo exportCode="1" xsi:type="ipo:UKAddress">
        <name>Helen Zoe</name>
        <street>47 Eden Street</street>
        <city>Cambridge</city>
        <postcode>CB1 1JR</postcode>
    </shipTo>
    <billTo xsi:type="ipo:USAddress">
        <name>Robert Smith</name>
        <street>8 Oak Avenue</street>
        <city>Old Town</city>
        <state>PA</state>
        <zip>95819</zip>
    </billTo>
    <items>
        <item partNum="833-AA">
            <productName>Lapis necklace</productName>
            <quantity>1</quantity>
            <USPrice>99.95</USPrice>
            <ipo:comment>Want this for the holidays!</ipo:comment>
            <shipDate>1999-12-05</shipDate>
        </item>
    </items>
</ipo:purchaseOrder>

declare namespace ipo="http://www.example.com/IPO"
count(
  document("ipo.xml")//ipo:shipTo[. instance of element of type ipo:UKAddress]
)

<zips>
  <row>
      <city>Old Town</city>      
      <state>PA</state>      
      <zip>95819</zip>
  </row>
  <row>
      <city>Durham</city>
      <state>NC</state>      
      <zip>27701</zip>
  </row> 
  <row>
      <city>Durham</city>
      <state>NC</state>      
      <zip>27703</zip>
  </row>
</zips>

import schema "ipo.xsd"
import schema "zips.xsd"
declare namespace ipo="http://www.example.com/IPO"
declare namespace zips="http://www.example.com/zips"
define function zip-ok($a as element of type ipo:USAddress)
  as xs:boolean
{
  some $i in document("zips.xml")/zips:zips/zips:row
  satisfies $i/zips:city = $a/ipo:city
        and $i/zips:state = $a/ipo:state
        and $i/zips:zip = $a/ipo:zip
}

<postals>
  <row>
    <city>Cambridge</city>
    <prefix>CB</prefix>
  </row>
  <row>
    <city>Oxford</city>
    <prefix>OX</prefix>
  </row> 
</postals>

import schema "ipo.xsd"
import schema "postals.xsd"
declare namespace ipo="http://www.example.com/IPO"
declare namespace pst="http://www.example.com/postals"
define function postal-ok($a as element of type ipo:UKAddress)
  as xs:boolean
{
  some $i in document("postals.xml")/pst:postals/pst:row
  satisfies $i/pst:city = $a/ipo:city
       and xf:starts-with($a/ipo:postcode, $i/pst:prefix)
}

import schema "ipo.xsd"
import schema "postals.xsd"
import schema "zips.xsd"
declare namespace ipo="http://www.example.com/IPO"
declare namespace pst="http://www.example.com/postals"
declare namespace zips="http://www.example.com/zips"
define function postal-ok($a as element of type ipo:UKAddress)
  as xs:boolean
{
  some $i in document("postals.xml")/pst:postals/pst:row
  satisfies $i/pst:city = $a/ipo:city
       and starts-with($a/ipo:postcode, $i/pst:prefix)
}
define function zip-ok($a as element of type ipo:USAddress)
  as xs:boolean
{
  some $i in document("zips.xml")/zips:zips/zips:row
  satisfies $i/zips:city = $a/ipo:city
        and $i/zips:state = $a/ipo:state
        and $i/zips:zip = $a/ipo:zip
}
define function address-ok($a as element of type ipo:Address)
 as xs:boolean
{
  typeswitch ($a)
      case element of type ipo:USAddress $zip
           return zip-ok($zip)
      case element of type ipo:UKAddress $postal
           return postal-ok($postal)
      default return false()
}
for $p in document("ipo.xml")//ipo:purchaseOrder
where not( address-ok($p/ipo:shipTo) and address-ok($p/ipo:billTo))
return $p

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
define function names-match( $s as element ipo:shipTo context ipo:purchaseOrder,
                             $b as element ipo:billTo context ipo:purchaseOrder)
  as xs:boolean
{
     $s/ipo:name = $b/ipo:name
}
for $p in document("ipo.xml")//ipo:purchaseOrder
where not( names-match( $p/ipo:shipTo, $p/ipo:billTo ) )
return $p                       

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
for $p in document("ipo.xml")//ipo:purchaseOrder,
    $s in $p/ipo:shipTo
where not( $s instance of element of type ipo:USAddress)
  and exists( $p//ipo:USPrice )
return $p

<element name="comment" type="string"/>                       
        . . .               
<element name="shipComment" type="string"
         substitutionGroup="ipo:comment"/>
<element name="customerComment" type="string"
         substitutionGroup="ipo:comment"/>

 <items>
   <item partNum="833-AA">
     <productName>Lapis necklace</productName>
     <quantity>1</quantity>
     <USPrice>99.95</USPrice>
     <ipo:shipComment>
       Use gold wrap if possible
     </ipo:shipComment>
     <ipo:customerComment>
       Want this for the holidays!
     </ipo:customerComment>
     <shipDate>1999-12-05</shipDate>
   </item>
 </items>   

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
define function comment-text($c as element ipo:comment)
  as xs:string
{
    string( $c )
}
for $p in document("ipo.xml")//ipo:purchaseOrder,
    $t in comment-text( $p//ipo:shipComment )
where $p/ipo:shipTo/ipo:name="Helen Zoe"
    and $p/ipo:orderDate = date("1999-12-01")
return $t

for $p in document("ipo.xml")//ipo:purchaseOrder
where $p/ipo:shipTo/ipo:name="Helen Zoe"
  and $p/@orderDate = date("1999-12-01")
return comment-text( $p//ipo:customerComment )   

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
for $p in document("ipo.xml")//ipo:purchaseOrder
where $p/ipo:shipTo/ipo:name="Helen Zoe"
  and $p/@orderDate = date("1999-12-01")
return ($p//ipo:customerComment  | $p//ipo:shipComment  | $p//ipo:comment )   

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
define function comments-for-element( $e as element )
  as ipo:comment*
{
  let $c := $e/(ipo:customerComment  | ipo:shipComment | ipo:comment)
  return $c
}   

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
define function deadbeat( $b as element ipo:billTo of type ipo:USAddress )
  as xs:boolean
{
   $b/ipo:name = document("www.usa-deadbeats.com/current")/deadbeats/row/name
}

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
define function total-price( $i as element ipo:item* )
  as xs:decimal
{
  let $subtotals := for $s in $i return $s/ipo:quantity * $s/ipo:USPrice
  return sum( $subtotals )
}

import schema "ipo.xsd"
declare namespace ipo="http://www.example.com/IPO"
for $p in document("ipo.xml")//ipo:purchaseOrder
where $p/ipo:shipTo/ipo:name="Helen Zoe"
   and $p/ipo:orderDate = date("1999-12-01")
return total-price($p//ipo:item)