Status of this Document
This section describes the status of this document at the
time of its publication. Other documents may supersede this
document. A list of current W3C publications and the latest
revision of this technical report can be found in the W3C technical reports index at
http://www.w3.org/TR/.
This is a Working
Group Note as described in the Process
Document. It was developed by the W3C XML Query Working Group, which
is part of the XML
Activity.
This document provides a number of use cases designed to
evaluate XQuery 3.0, the requirements for which are specified in
[XQuery 3.0
Requirements].
This document incorporates changes made against the previous
publication of the Working Draft. Changes to this document since
the previous publication of the Working Draft are detailed in
B Change Log.
Please report errors in this document using W3C's public Bugzilla system
(instructions can be found at http://www.w3.org/XML/2005/04/qt-bugzilla).
If access to that system is not feasible, you may send your
comments to the W3C XSLT/XPath/XQuery public comments mailing list,
[email protected].
It will be very helpful if you include the string “[XQuery30UC]” in
the subject line of your report, whether made in Bugzilla or in
email. Please use multiple Bugzilla entries (or, if necessary,
multiple email messages) if you have more than one comment to make.
Archives of the comments and responses are available at http://lists.w3.org/Archives/Public/public-qt-comments/.
Publication as a Working
Group Note does not imply endorsement by the W3C Membership.
This is a draft document and may be updated, replaced or obsoleted
by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
This document was produced by a group operating under the
5
February 2004 W3C Patent Policy. W3C maintains a public
list of any patent disclosures made in connection with the
deliverables of the group; that page also includes instructions for
disclosing a patent. An individual who has actual knowledge of a
patent which the individual believes contains
Essential Claim(s) must disclose the information in accordance
with
section 6 of the W3C Patent Policy.
1 Use Cases for XML
Query 3.0
The use cases listed below were created by the XML Query Working
Group to illustrate important applications for the new features in
XQuery 3.0. Each use case is focused on a specific application
area, and contains a XML Schema and example input data. Each use
case specifies a set of queries that might be applied to the input
data, and the expected results for each query. Since the English
description of each query is concise, the expected results form an
important part of the definition of each query, specifying the
expected output format.
Most of the listed use cases are based on a simple shopping
scenario described in section Schema and Data.
Use cases which require special data have a seperate subsection
describing the XML Schema and input data. All use cases assume that
input is provided in the form of one or more documents with
specific names. For instance, the products in a document may be
accessed with expressions like this:
doc("products.xml")//product
Several implementors have asked us to make the queries from
these use cases available in a separate file in order to make it
easier for them to test their parsers. These queries may be found
in [Use Case Sample Queries]
To make output more readable, the output of queries has been
formatted using whitespace which may not be returned by a query
processor. This whitespace should not be considered normative for
the correctness of results.
These queries were tested with a dynamic implementation of
XQuery. Some queries may require additional type declarations to be
used with an implementation that implements the Static Typing
feature.
2 Shopping Scenario: Schema and
Data
If not stated otherwise all use cases in this document are based
on a simplified shopping scenario containing three documents. The
first document, products.xml, contains a list of products, whereas
stores.xml includes a list of stores, and sales-records.xml
contains the list of sales.
2.1 Schema
The document product.xml uses the following XML Schema:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="products">
<xs:complexType>
<xs:sequence>
<xs:element name="product" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="category" type="xs:string"/>
<xs:element name="price" type="xs:double"/>
<xs:element name="cost" type="xs:double"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
The sales-records.xml document follows this XML Schema:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="sales">
<xs:complexType>
<xs:sequence>
<xs:element name="record" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="product-name" type="xs:string"/>
<xs:element name="store-number" type="xs:integer"/>
<xs:element name="qty" type="xs:integer"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
The stores.xml document is valid to this XML Schema:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="stores">
<xs:complexType>
<xs:sequence>
<xs:element name="store" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="store-number" type="xs:byte"/>
<xs:element name="state" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
2.2 Sample
Data
The content of the document products.xml is:
<products>
<product>
<name>broiler</name>
<category>kitchen</category>
<price>100</price>
<cost>70</cost>
</product>
<product>
<name>toaster</name>
<category>kitchen</category>
<price>30</price>
<cost>10</cost>
</product>
<product>
<name>blender</name>
<category>kitchen</category>
<price>50</price>
<cost>25</cost>
</product>
<product>
<name>socks</name>
<category>clothes</category>
<price>5</price>
<cost>2</cost>
</product>
<product>
<name>shirt</name>
<category>clothes</category>
<price>10</price>
<cost>3</cost>
</product>
</products>
The content of sales-records.xml is:
<sales>
<record>
<product-name>broiler</product-name>
<store-number>1</store-number>
<qty>20</qty>
</record>
<record>
<product-name>toaster</product-name>
<store-number>2</store-number>
<qty>100</qty>
</record>
<record>
<product-name>toaster</product-name>
<store-number>2</store-number>
<qty>50</qty>
</record>
<record>
<product-name>toaster</product-name>
<store-number>3</store-number>
<qty>50</qty>
</record>
<record>
<product-name>blender</product-name>
<store-number>3</store-number>
<qty>100</qty>
</record>
<record>
<product-name>blender</product-name>
<store-number>3</store-number>
<qty>150</qty>
</record>
<record>
<product-name>socks</product-name>
<store-number>1</store-number>
<qty>500</qty>
</record>
<record>
<product-name>socks</product-name>
<store-number>2</store-number>
<qty>10</qty>
</record>
<record>
<product-name>shirt</product-name>
<store-number>3</store-number>
<qty>10</qty>
</record>
</sales>
The content of stores.xml is:
<stores>
<store>
<store-number>1</store-number>
<state>CA</state>
</store>
<store>
<store-number>2</store-number>
<state>CA</state>
</store>
<store>
<store-number>3</store-number>
<state>MA</state>
</store>
<store>
<store-number>4</store-number>
<state>WA</state>
</store>
</stores>
3 Use Case "Group By" -
Queries which require value-based grouping
This use case contains several sample queries in which value
based grouping is needed.
3.1 Schema and Sample
Data
Queries 1-6 are based on a simplified shop scenario with
products, sales records and different shop locations. The schema
and data can be found in section Schema and
Data. Queries 7 and 8 are based on a bibliography document
shown below:
3.1.1 Schema Q7-Q8
Q7 and Q8 use an input document named "books.xml", with the
following XML Schema:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="bib">
<xs:complexType>
<xs:sequence>
<xs:element name="book" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="author" type="xs:string" maxOccurs="unbounded"/>
<xs:element name="title" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
3.1.2 Sample Data
Q7-Q8
Here are the contents of books.xml:
<bib>
<book>
<author>Jim Melton</author>
<author>Alan Simon</author>
<title>SQL:1999</title>
</book>
<book>
<author>Jim Melton</author>
<title>Advanced SQL:1999</title>
</book>
<book>
<author>Alan Simon</author>
<title>Strategic Database Technology</title>
</book>
<book>
<author>Jim Melton</author>
<author>Andrew Eisenberg</author>
<title>Understanding SQL and Java Together</title>
</book>
<book>
<author>Jim Melton</author>
<author>Stephen Buxton</author>
<title>Querying XML</title>
</book>
</bib>
3.2 Queries and Results
3.2.1 Q1
Group sales by product, list name and total quantity of each
product.
Solution in XQuery:
<sales-qty-by-product>{
for $sales in doc("sales-records.xml")/*/record
let $pname := $sales/product-name
group by $pname
order by $pname
return
<product name="{$pname}">{
sum($sales/qty)
}</product>
}</sales-qty-by-product>
Expected Result:
<sales-qty-by-product>
<product name="blender">250</product>
<product name="broiler">20</product>
<product name="shirt">10</product>
<product name="socks">510</product>
<product name="toaster">200</product>
</sales-qty-by-product>
3.2.2 Q2
Group sales by state (a property of the store) and category (a
property of the product). Order groups by the grouping keys. For
each group, show the total quantity sold.
Solution in XQuery:
<result>{
for $sales in doc("sales-records.xml")/*/record
let $state := doc("stores.xml")/*/store[store-number = $sales/store-number]/state
let $category := doc("products.xml")/*/product[name = $sales/product-name]/category
group by $state, $category
order by $state, $category
return
<group>
<state>{$state}</state>
<category>{$category}</category>
<total-qty>{sum($sales/qty)}</total-qty>
</group>
}</result>
Expected Result:
<result>
<group>
<state>CA</state>
<category>clothes</category>
<total-qty>510</total-qty>
</group>
<group>
<state>CA</state>
<category>kitchen</category>
<total-qty>170</total-qty>
</group>
<group>
<state>MA</state>
<category>clothes</category>
<total-qty>10</total-qty>
</group>
<group>
<state>MA</state>
<category>kitchen</category>
<total-qty>300</total-qty>
</group>
</result>
3.2.3 Q3
Group sales by state (a property of the store) and category (a
property of the product). Order groups by the grouping keys. For
each group, show the total revenue (defined as sales/qty *
product/price).
Solution in XQuery:
<result>{
for $sales in doc("sales-records.xml")/*/record
let $state := doc("stores.xml")/*/store[store-number = $sales/store-number]/state,
$product := doc("products.xml")/*/product[name = $sales/product-name],
$category := $product/category,
$revenue := $sales/qty * $product/price
group by $state, $category
order by $state, $category
return
<group>
<state>{$state}</state>
<category>{$category}</category>
<total-revenue>{sum($revenue)}</total-revenue>
</group>
}</result>
Expected Result:
<result>
<group>
<state>CA</state>
<category>clothes</category>
<total-revenue>2550</total-revenue>
</group>
<group>
<state>CA</state>
<category>kitchen</category>
<total-revenue>6500</total-revenue>
</group>
<group>
<state>MA</state>
<category>clothes</category>
<total-revenue>100</total-revenue>
</group>
<group>
<state>MA</state>
<category>kitchen</category>
<total-revenue>14000</total-revenue>
</group>
</result>
3.2.4 Q4
Combine the input documents into a three-level hierarchy based
on state, category, and product. At the product level, show the
total quantity sold of each product. List items alphabetically at
each level of the hierarchy.
Solution in XQuery:
<result>{
for $store in doc("stores.xml")/*/store
let $state := $store/state
group by $state
order by $state
return
<state name="{$state}">{
for $product in doc("products.xml")/*/product
let $category := $product/category
group by $category
order by $category
return
<category name="{$category}">{
for $sales in doc("sales-records.xml")/*/record[store-number = $store/store-number
and product-name = $product/name]
let $pname := $sales/product-name
group by $pname
order by $pname
return
<product name="{$pname}" total-qty="{sum($sales/qty)}" />
}</category>
}</state>
}</result>
Expected Result:
<result>
<state name="CA">
<category name="clothes">
<product name="socks" total-qty="510"/>
</category>
<category name="kitchen">
<product name="broiler" total-qty="20"/>
<product name="toaster" total-qty="150"/>
</category>
</state>
<state name="MA">
<category name="clothes">
<product name="shirt" total-qty="10"/>
</category>
<category name="kitchen">
<product name="blender" total-qty="250"/>
<product name="toaster" total-qty="50"/>
</category>
</state>
</result>
3.2.5 Q5
List all stores in ascending order by store number. For each
store, list the products sold in that store, in descending order by
quantity sold. Illustrates ordering among and within groups.
Solution in XQuery:
<result>{
for $sales in doc("sales-records.xml")/*/record
let $storeno := $sales/store-number
group by $storeno
order by $storeno
return
<store number = "{$storeno}">{
for $s in $sales
order by xs:int($s/qty) descending
return
<product name = "{$s/product-name}" qty = "{$s/qty}"/>
}</store>
}</result>
Expected Result:
<result>
<store number="1">
<product name="socks" qty="500"/>
<product name="broiler" qty="20"/>
</store>
<store number="2">
<product name="toaster" qty="100"/>
<product name="toaster" qty="50"/>
<product name="socks" qty="10"/>
</store>
<store number="3">
<product name="blender" qty="150"/>
<product name="blender" qty="100"/>
<product name="toaster" qty="50"/>
<product name="shirt" qty="10"/>
</store>
</result>
3.2.6 Q6
List all stores whose total profit is greater than 100, in
descending order by total profit. Note: total profit for a store is
the sum over all sales in that store, of the quantity sold times
the difference between price and cost for the item sold.
Illustrates cross-document computation, filtering of groups,
ordering by a non-grouping key.
Solution in XQuery:
<result>{
for $sales in doc("sales-records.xml")/*/record
let $storeno := $sales/store-number,
$product := doc("products.xml")/*/product[name = $sales/product-name],
$prd := $product,
$profit := $sales/qty * ($prd/price - $prd/cost)
group by $storeno
let $total-store-profit := sum($profit)
where $total-store-profit > 100
order by $total-store-profit descending
return
<store number = "{$storeno}" total-profit = "{$total-store-profit}"/>
}</result>
Expected Result:
<result>
<store number="3" total-profit="7320"/>
<store number="2" total-profit="3030"/>
<store number="1" total-profit="2100"/>
</result>
3.2.7 Q7
Group books by author. Create a group for each individual
author. A book with multiple authors should appear in the groups
for each of its authors. Alphabetize the authors and the book
titles within each author group.
Solution in XQuery:
<result>{
for $book in doc("books.xml")/*/book
for $author in $book/author
group by $author
order by $author
return
<author name="{$author}">{
for $b in $book
order by $b/title
return
<title> {fn:data($b/title)} </title>
}</author>
}</result>
Expected Result:
<result>
<author name="Alan Simon">
<title>SQL:1999</title>
<title>Strategic Database Technology</title>
</author>
<author name="Andrew Eisenberg">
<title>Understanding SQL and Java Together</title>
</author>
<author name="Jim Melton">
<title>Advanced SQL:1999</title>
<title>Querying XML</title>
<title>SQL:1999</title>
<title>Understanding SQL and Java Together</title>
</author>
<author name="Stephen Buxton">
<title>Querying XML</title>
</author>
</result>
3.2.8 Q8
Group books by author. Create a group for each distinct ordered
list of authors. Each book should be grouped with other books that
have the same ordered list of authors. Alphabetize the book titles
within each group.
Solution in XQuery:
<result>{
for $book in doc("books.xml")/*/book
let $author-list := fn:string-join($book/author, ', ')
group by $author-list
order by $author-list
return
<author-list names="{$author-list}">{
for $b in $book
order by $b/title
return
<title> {fn:data($b/title)} </title>
}</author-list>
}</result>
Expected Result:
<result>
<author-list names="Alan Simon">
<title>Strategic Database Technology</title>
</author-list>
<author-list names="Jim Melton">
<title>Advanced SQL:1999</title>
</author-list>
<author-list names="Jim Melton, Alan Simon">
<title>SQL:1999</title>
</author-list>
<author-list names="Jim Melton, Andrew Eisenberg">
<title>Understanding SQL and Java Together</title>
</author-list>
<author-list names="Jim Melton, Stephen Buxton">
<title>Querying XML</title>
</author-list>
</result>
4 Use Case "Windowing" -
Queries which require windowing
This use case covers queries that require windowing or
positional grouping, which can be seen as a special form of
windowing. Windowing means that the queries require selecting
subsequences based on certain characterisics of an underlying
sequence.
4.1 Schema and
Sample Data
Windowing is required in various scenarios from formatting up to
streaming applications. The listed queries try to cover different
scenarios and require therefore also various types of input data.
The following sections describe for every query the used data and
the according schema.
4.1.1 XML
Schema for Q1
Q1 uses an input document named arrange_rows.xml, with the
following XML Schema arrange_rows.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="doc">
<xs:complexType>
<xs:sequence>
<xs:element name="data" type="xs:string" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
4.1.2
Sample Data for Q1
The content of arrange_rows.xml is:
<doc>
<data>Green</data>
<data>Pink</data>
<data>Lilac</data>
<data>Turquoise</data>
<data>Peach</data>
<data>Opal</data>
<data>Champagne</data>
</doc>
4.1.3 XML Schema
for Q2
Q2 uses an input document named head_para.xml, with the
following XML Schema named head_para.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="body">
<xs:complexType>
<xs:sequence>
<xs:sequence maxOccurs="unbounded">
<xs:element name="h2" type="xs:string"/>
<xs:element name="p" type="xs:string" maxOccurs="unbounded"/>
</xs:sequence>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
4.1.4 Sample
Data for Q2
The content of head_para.xml is:
<body>
<h2>heading1</h2>
<p>para1</p>
<p>para2</p>
<h2>heading2</h2>
<p>para3</p>
<p>para4</p>
<p>para5</p>
</body>
4.1.5 XML
Schema for Q3
Q3 uses an input document named term_def_list.xml, with the
following XML Schema named term_def_list.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="doc">
<xs:complexType>
<xs:sequence>
<xs:sequence maxOccurs="unbounded">
<xs:element name="dt" type="xs:string" maxOccurs="unbounded"/>
<xs:element name="dd" type="xs:string" maxOccurs="unbounded"/>
</xs:sequence>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
4.1.6
Sample Data for Q3
The content of term_def_list.xml is:
<doc>
<dt>XML</dt>
<dd>Extensible Markup Language</dd>
<dt>XSLT</dt>
<dt>XSL Transformations</dt>
<dd>A language for transforming XML</dd>
<dd>A specification produced by W3C</dd>
</doc>
4.1.7 XML Schema for Q4-Q6
Q4 - Q6 use an input document named temp_events.xml, with the
following XML Schema named temp_events.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="stream">
<xs:complexType>
<xs:sequence>
<xs:element name="event" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="time" type="xs:integer" use="required"/>
<xs:attribute name="temp" type="xs:double" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
4.1.8 Sample Data for Q4-Q6
The content of temp_events.xml is:
<stream>
<event temp="10" time="1"/>
<event temp="8" time="2"/>
<event temp="6" time="3"/>
<event temp="13" time="4"/>
<event temp="32" time="5"/>
<event temp="9" time="6"/>
<event temp="10" time="7"/>
</stream>
4.1.9 XML Schema for
Q7-Q13
Q7 - Q13 use an input document named person_events.xml, with the
following XML Schema named person_events.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="stream">
<xs:complexType>
<xs:sequence>
<xs:element name="event" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence minOccurs="0">
<xs:element name="person" type="xs:string"/>
<xs:element name="direction" type="xs:string"/>
</xs:sequence>
<xs:attribute name="time" type="xs:dateTime" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
4.1.10 Sample Data for
Q7-Q13
The content of person_events.xml is:
<stream>
<event time="2006-01-01T01:00:00-00:00"/>
<event time="2006-01-01T10:30:00-00:00">
<person>Anton</person>
<direction>in</direction>
</event>
<event time="2006-01-01T11:00:00-00:00">
<person>Barbara</person>
<direction>in</direction>
</event>
<event time="2006-01-01T11:15:00-00:00">
<person>Clara</person>
<direction>in</direction>
</event>
<event time="2006-01-01T12:15:00-00:00">
<person>Clara</person>
<direction>out</direction>
</event>
<event time="2006-01-01T14:00:00-00:00">
<person>Barbara</person>
<direction>out</direction>
</event>
<event time="2006-01-01T15:00:00-00:00">
<person>Anton</person>
<direction>out</direction>
</event>
<event time="2006-01-01T23:00:00-00:00"/>
<event time="2006-01-02T01:00:00-00:00"/>
<event time="2006-01-02T11:00:00-00:00">
<person>Anton</person>
<direction>in</direction>
</event>
<event time="2006-01-02T12:00:00-00:00">
<person>Clara</person>
<direction>in</direction>
</event>
<event time="2006-01-02T12:10:00-00:00">
<person>Clara</person>
<direction>out</direction>
</event>
<event time="2006-01-02T12:15:00-00:00">
<person>Clara</person>
<direction>in</direction>
</event>
<event time="2006-01-02T12:20:00-00:00">
<person>Clara</person>
<direction>out</direction>
</event>
<event time="2006-01-02T12:25:00-00:00">
<person>Clara</person>
<direction>in</direction>
</event>
<event time="2006-01-02T12:40:00-00:00">
<person>Clara</person>
<direction>out</direction>
</event>
<event time="2006-01-02T14:00:00-00:00">
<person>Clara</person>
<direction>in</direction>
</event>
<event time="2006-01-02T16:00:00-00:00">
<person>Anton</person>
<direction>out</direction>
</event>
<event time="2006-01-02T16:15:00-00:00">
<person>Clara</person>
<direction>out</direction>
</event>
<event time="2006-01-02T23:00:00-00:00"/>
</stream>
4.1.11 XML Schema for
Q14-Q16
Q14 - Q16 use as input document a slightly modified RSS document
named rss.xml. It mainly differs from RSS 2.0 in the way dates are
expressed in the data. The XML Schema, rss.xsd, is as follows:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="rss">
<xs:complexType>
<xs:sequence>
<xs:element name="channel">
<xs:complexType>
<xs:sequence>
<xs:element name="title" type="xs:string"/>
<xs:element name="link" type="xs:anyURI"/>
<xs:element name="description" type="xs:string"/>
<xs:element name="language" type="xs:string"/>
<xs:element ref="item" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="item">
<xs:complexType>
<xs:sequence>
<xs:element name="title" type="xs:string"/>
<xs:element name="category" type="xs:string"/>
<xs:element name="author" type="xs:string"/>
<xs:element name="pubDate" type="xs:dateTime"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
4.1.12 Sample Data for
Q14-Q16
The content of rss.xml is:
<rss>
<channel>
<title>DBIS RSS</title>
<link>http://www.dbis.ethz.ch</link>
<description>The windowing dummy RSS.</description>
<language>en-us</language>
<item>
<title>Why use cases are important Part 1.</title>
<category>Workshop</category>
<author>[email protected]</author>
<pubDate>2003-06-03T09:00:00</pubDate>
</item>
<item>
<title>Why use cases are important Part 2.</title>
<category>Workshop</category>
<author>[email protected]</author>
<pubDate>2003-06-03T09:00:00</pubDate>
</item>
<item>
<title>Why use cases are important Part 3.</title>
<category>Workshop</category>
<author>[email protected]</author>
<pubDate>2003-06-03T10:00:00</pubDate>
</item>
<item>
<title>Extending XQuery with Window Functions</title>
<category>Talk</category>
<author>[email protected]</author>
<pubDate>2003-06-03T11:00:00</pubDate>
</item>
<item>
<title>XQueryP: A new programming language is born</title>
<category>Talk</category>
<author>[email protected]</author>
<pubDate>2003-06-03T12:00:00</pubDate>
</item>
<item>
<title>Why use cases are annoying to write.</title>
<category>Talk</category>
<author>[email protected]</author>
<pubDate>2003-06-04T10:00:00</pubDate>
</item>
</channel>
</rss>
4.1.13 XML Schema for
Q17-Q19
Q17-Q19 use an input document named cxml.xml. The structure of
this document is inspired by the Commerce XML Resource standard
(cXML). The document contains a sequence of events, where an event
corresponds to a simplified message of the cXML standard or an
timeclock event. The XML Schema with the file-name cxml.xsd is as
follows:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="sequence">
<xs:complexType>
<xs:sequence>
<xs:choice maxOccurs="unbounded">
<xs:element name="time" type="TimeEvent"/>
<xs:element name="OrderRequest" type="OrderRequest" maxOccurs="unbounded"/>
<xs:element name="ConfirmationRequest" type="ConfirmationRequest"/>
<xs:element name="ShipNotice" type="ShipNotice" maxOccurs="unbounded"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:complexType name="TimeEvent">
<xs:attribute name="date" type="xs:dateTime" use="required"/>
</xs:complexType>
<xs:complexType name="OrderRequest">
<xs:sequence>
<xs:element name="Item" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="unitPrice" type="xs:byte" use="required"/>
<xs:attribute name="quantity" type="xs:byte" use="required"/>
<xs:attribute name="partID" type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="type" type="xs:string" use="required"/>
<xs:attribute name="total" type="xs:short" use="required"/>
<xs:attribute name="shipTo" type="xs:string"/>
<xs:attribute name="orderID" type="xs:string" use="required"/>
<xs:attribute name="date" type="xs:dateTime" use="required"/>
<xs:attribute name="billTo" type="xs:string" use="required"/>
</xs:complexType>
<xs:complexType name="ConfirmationRequest">
<xs:attribute name="status" type="xs:string" use="required"/>
<xs:attribute name="orderID" type="xs:string" use="required"/>
<xs:attribute name="date" type="xs:dateTime" use="required"/>
<xs:attribute name="confirmID" type="xs:string" use="required"/>
</xs:complexType>
<xs:complexType name="ShipNotice">
<xs:attribute name="orderID" type="xs:string" use="required"/>
<xs:attribute name="date" type="xs:dateTime" use="required"/>
</xs:complexType>
</xs:schema>
4.1.14 Sample Data for
Q17-Q19
The content of cxml.xml is:
<sequence>
<time date="2006-01-01T00:00:00-00:00"/>
<OrderRequest billTo="ACME1" date="2006-01-01T10:00:00-00:00"
orderID="OID01" shipTo="ACME1" total="1100" type="new">
<Item partID="ID1" quantity="10" unitPrice="100"/>
<Item partID="ID2" quantity="10" unitPrice="10"/>
</OrderRequest>
<OrderRequest billTo="ACME2" date="2006-01-01T11:00:00-00:00"
orderID="OID02" total="100" type="new">
<Item partID="ID2" quantity="10" unitPrice="10"/>
</OrderRequest>
<ConfirmationRequest confirmID="C1" date="2006-01-01T18:00:00-00:00"
orderID="OID02" status="reject"/>
<time date="2006-01-02T00:00:00-00:00"/>
<ConfirmationRequest confirmID="C1" date="2006-01-02T08:00:00-00:00"
orderID="OID01" status="accept"/>
<OrderRequest billTo="ACME1" date="2006-01-02T14:00:00-00:00"
orderID="OID03" shipTo="ACME1" total="10000" type="new">
<Item partID="ID3" quantity="100" unitPrice="100"/>
</OrderRequest>
<ConfirmationRequest confirmID="C1" date="2006-01-02T16:00:00-00:00"
orderID="OID03" status="accept"/>
<time date="2006-01-03T00:00:00-00:00"/>
<time date="2006-01-04T00:00:00-00:00"/>
<time date="2006-01-05T00:00:00-00:00"/>
<ShipNotice date="2006-01-05T08:00:00-00:00" orderID="OID01"/>
<ShipNotice date="2006-01-05T09:00:00-00:00" orderID="OID03"/>
<time date="2006-01-06T00:00:00-00:00"/>
<OrderRequest billTo="ACME2" date="2006-01-06T08:00:00-00:00"
orderID="OID04" total="100" type="new">
<Item partID="ID2" quantity="10" unitPrice="10"/>
</OrderRequest>
<time date="2006-01-07T00:00:00-00:00"/>
</sequence>
4.2 Queries and Results
4.2.1 Q1
Arrange a sequence of items as a table with three columns (using
as many rows as necessary).
Solution in XQuery:
declare variable $seq := fn:doc("arrange_rows.xml");
<table>{
for tumbling window $w in $seq/doc/*
start at $x when fn:true()
end at $y when $y - $x = 2
return
<tr>{
for $i in $w
return
<td>{data($i)}</td>
}</tr>
}</table>
Expected Result:
<table>
<tr>
<td>Green</td>
<td>Pink</td>
<td>Lilac</td>
</tr>
<tr>
<td>Turquoise</td>
<td>Peach</td>
<td>Opal</td>
</tr>
<tr>
<td>Champagne</td>
</tr>
</table>
4.2.2 Q2
Convert a structure with implicit sections to a structure with
explicit sections.
Solution in XQuery:
declare variable $seq := fn:doc("head_para.xml");
<chapter>{
for tumbling window $w in $seq/body/*
start previous $s when $s[self::h2]
end next $e when $e[self::h2]
return
<section title="{data($s)}">{
for $x in $w
return
<para>{data($x)}</para>
}</section>
}</chapter>
Expected Result:
<chapter>
<section title="heading1">
<para>para1</para>
<para>para2</para>
</section>
<section title="heading2">
<para>para3</para>
<para>para4</para>
<para>para5</para>
</section>
</chapter>
4.2.3 Q3
Within a glossary in HTML, a defined term <dt> can be
followed by a definition <dd>. The task is to group these
together within a <term> element, where a group can consist
of one or more <dt> elements followed by one or more
<dd> elements.
Solution in XQuery:
declare variable $seq := fn:doc("term_def_list.xml");
<doc>{
for tumbling window $w in $seq/doc/*
start $x when $x[self::dt]
end $y next $z when $y[self::dd] and $z[self::dt]
return
<term>{
$w
}</term>
}</doc>
Expected Result:
<doc>
<term>
<dt>XML</dt>
<dd>Extensible Markup Language</dd>
</term>
<term>
<dt>XSLT</dt>
<dt>XSL Transformations</dt>
<dd>A language for transforming XML</dd>
<dd>A specification produced by W3C</dd>
</term>
</doc>
4.2.4 Q4
Calculate the moving average of temperature values for the 3
last seconds.
Solution in XQuery:
declare variable $timesequence := fn:doc("temp_events.xml");
let $MAX_DIFF := 2
for sliding window $w in $timesequence/stream/event
start $s_curr at $s_pos previous $s_prev
when ($s_curr/@time ne $s_prev/@time) or (empty($s_prev))
only end next $e_next
when $e_next/@time - $s_curr/@time gt $MAX_DIFF
return
avg( $w/@temp )
Expected Result:
4.2.5 Q5
Single exponential smoothing (3 last values and smoothing factor
0.2)
Solution in XQuery:
declare variable $timesequence := fn:doc("temp_events.xml");
let $SMOOTH_CONST := 0.2
for sliding window $w in $timesequence/stream/event
start at $s_pos when true()
only end at $e_pos when $e_pos - $s_pos eq 2
return
round-half-to-even($SMOOTH_CONST * data($w[3]/@temp) + (1 - $SMOOTH_CONST) *
( $SMOOTH_CONST * data($w[2]/@temp) +
(1 - $SMOOTH_CONST) * data($w[1]/@temp) ), 2)
Expected Result:
8.88 8.68 12.32 15.24 23.92
4.2.6 Q6
Detect outliers (current value is two times higher (lower) than
the average of the previous three values) in a sequence of temp
values.
Solution in XQuery:
declare variable $seq := fn:doc("temp_events.xml");
for sliding window $w in $seq/stream/event
start $s_curr when fn:true()
only end next $next when $next/@time > $s_curr/@time + 3
return
let $avg := fn:avg($w/@temp)
where $avg * 2 lt xs:double($next/@temp) or $avg div 2 gt xs:double($next/@temp)
return <alarm>Outlier detected. Event id:{data($next/@time)}</alarm>
Expected Result:
<alarm>Outlier detected. Event id:5</alarm>
4.2.7
Q7
Notify when Barbara enters the building within 1 hour after
Anton
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<result>{
for tumbling window $w in $seq/stream/event
start $s when $s/person eq "Anton" and $s/direction eq "in"
only end $e next $n when xs:dateTime($n/@time) - xs:dateTime($s/@time) gt
xs:dayTimeDuration("PT1H")
or ($e/person eq "Barbara" and $e/direction eq "in")
or ($e/person eq "Anton" and $e/direction eq "out")
where $e/person eq "Barbara" and $e/direction eq "in"
return
<warning time="{ $e/@time }">Barbara: Anton arrived 1h ago</warning>
}</result>
Expected Result:
<result>
<warning time="2006-01-01T11:00:00-00:00">Barbara: Anton arrived 1h ago</warning>
</result>
4.2.8 Q8
Measure the working time of each person
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<result>{
for sliding window $w in $seq/stream/event
start $s when $s/direction eq "in"
only end $e when $s/person eq $e/person and
$e/direction eq "out"
return
<working-time>
{$s/person}
<time>{ xs:dateTime($e/@time) - xs:dateTime($s/@time)}</time>
</working-time>
}</result>
Expected Result:
<result>
<working-time>
<person>Anton</person>
<time>PT4H30M</time>
</working-time>
<working-time>
<person>Barbara</person>
<time>PT3H</time>
</working-time>
<working-time>
<person>Clara</person>
<time>PT1H</time>
</working-time>
<working-time>
<person>Anton</person>
<time>PT5H</time>
</working-time>
<working-time>
<person>Clara</person>
<time>PT10M</time>
</working-time>
<working-time>
<person>Clara</person>
<time>PT5M</time>
</working-time>
<working-time>
<person>Clara</person>
<time>PT15M</time>
</working-time>
<working-time>
<person>Clara</person>
<time>PT2H15M</time>
</working-time>
</result>
4.2.9 Q9
Measure the overall working time for each person.
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<result>{
for sliding window $w in $seq/stream/event
start $s when $s/direction eq "in"
only end $e when $s/person eq $e/person and
$e/direction eq "out"
let $person := $s/person
let $workingTime := xs:dateTime($e/@time) - xs:dateTime($s/@time)
group by $person
order by $person
return
<working-time>
<person>{ $person }</person>
<time>{ sum($workingTime) }</time>
</working-time>
}</result>
Expected Result:
<result>
<working-time>
<person>Anton</person>
<time>PT9H30M</time>
</working-time>
<working-time>
<person>Barbara</person>
<time>PT3H</time>
</working-time>
<working-time>
<person>Clara</person>
<time>PT3H45M</time>
</working-time>
</result>
4.2.10 Q10
Display a warning if Barbara does not come to work.
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<result>{
for tumbling window $w in $seq/stream/event[direction eq "in"]
start $s when fn:true()
end next $e when xs:date( xs:dateTime($s/@time) ) ne xs:date( xs:dateTime($e/@time) )
let $date := xs:date(xs:dateTime($s/@time))
where not($w[person eq "Barbara"])
return <alert date="{ $date }">Barbara did not come to work</alert>
}</result>
Expected Result:
<result>
<alert date="2006-01-02Z">Barbara did not come to work</alert>
</result>
4.2.11
Q11
Identify every person who enters the building before Clara
withing a 15 minute timeframe (Clara's arrival time - 15
minutes).
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<results>{
for tumbling window $w in $seq/stream/event[direction eq "in"]
start when true()
only end next $x when $x/person eq "Clara"
return
<result time="{ $x/@time }">{
distinct-values(for $y in $w
where (xs:dateTime($y/@time) + xs:dayTimeDuration("PT15M") ) ge xs:dateTime($x/@time)
return $y/person)
}</result>
}</results>
Expected Result:
<results>
<result time="2006-01-01T11:15:00-00:00">Barbara</result>
<result time="2006-01-02T12:00:00-00:00"/>
<result time="2006-01-02T12:15:00-00:00">Clara</result>
<result time="2006-01-02T12:25:00-00:00">Clara</result>
<result time="2006-01-02T14:00:00-00:00"/>
</results>
4.2.12 Q12
Notify when both Anton and Barbara enter the office within 30
minutes of one another.
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<result>{
for tumbling window $w in $seq/stream/event[direction eq "in"]
start $x when $x/person = ("Barbara", "Anton")
end next $y when xs:dateTime($y/@time) - xs:dateTime($x/@time) gt xs:dayTimeDuration("PT30M")
where $w[person eq "Anton"] and $w[person eq "Barbara"]
return
<alert time="{ xs:dateTime($y/@time) }">Anton and Barbara just arrived</alert>
}</result>
Expected Result:
<result>
<alert time="2006-01-01T11:15:00Z">Anton and Barbara just arrived</alert>
</result>
4.2.13 Q13
Inform when a person enters the building at least 3 times within
1 hour
Solution in XQuery:
declare variable $seq := fn:doc("person_events.xml");
<result>{
for sliding window $w in $seq/stream/event
start $s when true()
end next $e when xs:dateTime($e/@time) - xs:dateTime($s/@time) gt
xs:dayTimeDuration("PT1H")
where count($w[person eq $s/person and direction eq "in"]) ge 3
return
<alert time="{ $e/@time }">{fn:data($s/person)} is suspicious</alert>
}</result>
Expected Result:
<result>
<alert time="2006-01-02T14:00:00-00:00">Clara is suspicious</alert>
</result>
4.2.14 Q14
Find all annoying authors who have posted three consecutive
items in the RSS feed.
Solution in XQuery:
declare variable $rssfeed := fn:doc("rss.xml");
<result>{
for tumbling window $w in $rssfeed/rss/channel/item
start $first when fn:true()
end next $lookAhead when $first/author ne $lookAhead/author
where count($w) ge 3
return <annoying-author>{
$w[1]/author
}</annoying-author>
}</result>
Expected Result:
<result>
<annoying-author>
<author>[email protected]</author>
</annoying-author>
</result>
4.2.15 Q15
Every day, provide a list of interesting topics in the RSS feed.
In our example, interesting means that the title of the item
contains the specific word XQuery.
Solution in XQuery:
declare variable $rssfeed := fn:doc("rss.xml");
<result>{
for tumbling window $w in $rssfeed/rss/channel/item
start $s_curr when true()
end next $e_next when
fn:day-from-dateTime(xs:dateTime($e_next/pubDate)) ne
fn:day-from-dateTime(xs:dateTime($s_curr/pubDate))
return
<item>
<date>{xs:date(xs:dateTime($s_curr/pubDate))}</date>
{ for $item in $w
where fn:contains( xs:string($item/title), 'XQuery')
return $item/title }
</item>
}</result>
Expected Result:
<result>
<item>
<date>2003-06-03</date>
<title>Extending XQuery with Window Functions</title>
<title>XQueryP: A new programming language is born</title>
</item>
<item>
<date>2003-06-04</date>
</item>
</result>
4.2.16 Q16
Every day, provide a summary of the RSS feed grouped by
author.
Solution in XQuery:
declare variable $rssfeed := fn:doc("rss.xml");
<result>{
for tumbling window $w in $rssfeed/rss/channel/item
start $s_curr when true()
end next $e_next when
fn:day-from-dateTime(xs:dateTime($e_next/pubDate)) ne
fn:day-from-dateTime(xs:dateTime($s_curr/pubDate))
return
<item>
<date>{xs:date(xs:dateTime($s_curr/pubDate))}</date>
{ for $a in fn:distinct-values($w/author)
return
<author name="{$a}">
<titles>
{ $w[author eq $a]/title }
</titles>
</author>
}
</item>
}</result>
Expected Result:
<result>
<item>
<date>2003-06-03</date>
<author name="[email protected]">
<titles>
<title>Why use cases are important Part 1.</title>
<title>Why use cases are important Part 2.</title>
<title>Why use cases are important Part 3.</title>
</titles>
</author>
<author name="[email protected]">
<titles>
<title>Extending XQuery with Window Functions</title>
</titles>
</author>
<author name="[email protected]">
<titles>
<title>XQueryP: A new programming language is born</title>
</titles>
</author>
</item>
<item>
<date>2003-06-04</date>
<author name="[email protected]">
<titles>
<title>Why use cases are annoying to write.</title>
</titles>
</author>
</item>
</result>
4.2.17 Q17
At the end of a day, list the most valuable customers.
Solution in XQuery:
declare variable $seq := fn:doc("cxml.xml");
<result>{
for sliding window $w in $seq/sequence/*
start $cur previous $prev
when day-from-dateTime($cur/@date) ne day-from-dateTime($prev/@date) or empty($prev)
end $end next $next
when day-from-dateTime(xs:dateTime($end/@date)) ne
day-from-dateTime(xs:dateTime($next/@date))
return
<mostValuableCustomer endOfDay="{xs:dateTime($cur/@date)}">{
let $companies := for $x in distinct-values($w/@billTo )
return <amount company="{$x}">{sum($w[@billTo eq $x]/@total)}</amount>
let $max := max($companies)
for $company in $companies
where $company eq xs:untypedAtomic($max)
return $company
}</mostValuableCustomer>
}</result>
Expected Result:
<result>
<mostValuableCustomer endOfDay="2006-01-01T00:00:00Z">
<amount company="ACME1">1100</amount>
</mostValuableCustomer>
<mostValuableCustomer endOfDay="2006-01-02T00:00:00Z">
<amount company="ACME1">10000</amount>
</mostValuableCustomer>
<mostValuableCustomer endOfDay="2006-01-03T00:00:00Z"/>
<mostValuableCustomer endOfDay="2006-01-04T00:00:00Z"/>
<mostValuableCustomer endOfDay="2006-01-05T00:00:00Z"/>
<mostValuableCustomer endOfDay="2006-01-06T00:00:00Z">
<amount company="ACME2">100</amount>
</mostValuableCustomer>
<mostValuableCustomer endOfDay="2006-01-07T00:00:00Z"/>
</result>
4.2.18 Q18
Calculate the time needed to process an order from the request
up to the shipping.
Solution in XQuery:
declare variable $seq := fn:doc("cxml.xml");
<result>{
for sliding window $w in $seq/sequence/*
start $s when $s[self::OrderRequest]
end $e when $e/@orderID eq $s/@orderID
and ($e[self::ConfirmationRequest] and $e/@status eq "reject"
or $e[self::ShipNotice])
where $e[self::ShipNotice]
return
<timeToShip orderID="{ $s/@orderID}">{xs:dateTime($e/@date) - xs:dateTime($s/@date) }</timeToShip>
}</result>
Expected Result:
<result>
<timeToShip orderID="OID01">P3DT22H</timeToShip>
<timeToShip orderID="OID03">P2DT19H</timeToShip>
</result>
4.2.19 Q19
At the moment of the shipping notification, calculate if an open
request exists that can be shipped to the same address.
Solution in XQuery:
declare variable $seq := fn:doc("cxml.xml");
<result>{
for sliding window $w in $seq/sequence/*
start previous $wSPrev when $wSPrev[self::OrderRequest]
end next $wENext when $wENext/@orderID eq $wSPrev/@orderID
and ($wENext[self::ConfirmationRequest] and $wENext/@status eq "reject"
or $wENext[self::ShipNotice])
where $wENext[self::ShipNotice]
return
<bundleWith orderId="{$wSPrev/@orderID}">{
for sliding window $bundle in $w
start $bSCur
when $bSCur[self::OrderRequest] and $bSCur/@shipTo eq $wSPrev/@shipTo
end $bECur next $bENext
when $bECur/@orderID eq $bSCur/@orderID
and ($bECur[self::ConfirmationRequest] and $bECur/@status eq "reject"
or $bECur[self::ShipNotice])
where empty($bENext)
return $bSCur
}</bundleWith>
}</result>
Expected Result:
<result>
<bundleWith orderId="OID01">
<OrderRequest billTo="ACME1" date="2006-01-02T14:00:00-00:00"
orderID="OID03" shipTo="ACME1" total="10000" type="new">
<Item partID="ID3" quantity="100" unitPrice="100"/>
</OrderRequest>
</bundleWith>
<bundleWith orderId="OID03"/>
</result>
5 Use Case
"Count" - Queries which require output numbering
The described queries in this section all require tuple
numbering. The numbering is either required in the final result or
might also be required at some point in the middle when the tuple
stream gets generated.
5.2 Queries and
Results
5.2.1
Q1
List all products in alphabatical order with a continously
increasing number.
Solution in XQuery:
<products>{
for $product in doc("products.xml")/*/product
order by $product/name
count $number
return
<product number="{$number}">{$product/*}</product>
}</products>
Expected Result:
<products>
<product number="1">
<name>blender</name>
<category>kitchen</category>
<price>50</price>
<cost>25</cost>
</product>
<product number="2">
<name>broiler</name>
<category>kitchen</category>
<price>100</price>
<cost>70</cost>
</product>
<product number="3">
<name>shirt</name>
<category>clothes</category>
<price>10</price>
<cost>3</cost>
</product>
<product number="4">
<name>socks</name>
<category>clothes</category>
<price>5</price>
<cost>2</cost>
</product>
<product number="5">
<name>toaster</name>
<category>kitchen</category>
<price>30</price>
<cost>10</cost>
</product>
</products>
5.2.2
Q2
Arrange a sequence of items as a table with three columns (using
as many rows as necessary) like in Q1 from the windowing use
cases.Additionally, number every row continuously.
Solution in XQuery:
declare variable $seq := fn:doc("arrange_rows.xml");
<table>{
for tumbling window $w in $seq/doc/*
start at $x when fn:true()
end at $y when $y - $x = 2
count $rowNumber
return
<tr>
<td>{$rowNumber}</td>{
for $i in $w
return
<td>{data($i)}</td>
}</tr>
}</table>
Expected Result:
<table>
<tr>
<td>1</td>
<td>Green</td>
<td>Pink</td>
<td>Lilac</td>
</tr>
<tr>
<td>2</td>
<td>Turquoise</td>
<td>Peach</td>
<td>Opal</td>
</tr>
<tr>
<td>3</td>
<td>Champagne</td>
</tr>
</table>
5.2.3 Q3
Top-K query: Return the three best-selling products (by
quantity).
Solution in XQuery:
<result>{
for $sales in doc("sales-records.xml")/*/record
let $name := $sales/product-name
group by $name
let $qty := sum($sales/qty)
order by $qty descending
count $count
where $count <= 3
return
<sale product="{$name}" qty="{$qty }"/>
}</result>
Expected Result:
<result>
<sale product="socks" qty="510"/>
<sale product="blender" qty="250"/>
<sale product="toaster" qty="200"/>
</result>
6 Use Case
"Outer For" - Queries which require outer joins
This use case demonstrate how the new "outer for" clause can
help to express outer joins in XQuery.
6.2 Queries and
Results
6.2.1 Q1
Report all the store sales including stores which have not sold
anything.
Solution in XQuery:
<result>{
for $store in doc("stores.xml")/*/store
for $sale allowing empty in doc("sales-records.xml")/*/record[
store-number eq $store/store-number]
return
<store number="{$store/store-number}"
product="{$sale/product-name}"
state="{$store/state}"
sold="{$sale/qty}" />
}</result>
Expected Result:
<result>
<store number="1" state="CA" product="broiler" sold="20"/>
<store number="1" state="CA" product="socks" sold="500"/>
<store number="2" state="CA" product="toaster" sold="100"/>
<store number="2" state="CA" product="toaster" sold="50"/>
<store number="2" state="CA" product="socks" sold="10"/>
<store number="3" state="MA" product="toaster" sold="50"/>
<store number="3" state="MA" product="blender" sold="100"/>
<store number="3" state="MA" product="blender" sold="150"/>
<store number="3" state="MA" product="shirt" sold="10"/>
<store number="4" state="WA" product="" sold=""/>
</result>
6.2.2
Q2
List all the sales records. Include also all the items which
were not sold in a store.
Solution in XQuery:
<result>{
for $store in doc("stores.xml")/*/store
for $product in doc("products.xml")/*/product
for $sale allowing empty in doc("sales-records.xml")/*/record[
store-number eq $store/store-number and
product-name eq $product/name]
return
<store number="{$store/store-number}"
state="{$store/state}"
product="{$sale/product-name}"
sold="{$sale/qty}" />
}</result>
Expected Result:
<?xml version="1.0" encoding="UTF-8"?>
<result>
<store number="1" state="CA" product="broiler" sold="20"/>
<store number="1" state="CA" product="toaster" sold=""/>
<store number="1" state="CA" product="blender" sold=""/>
<store number="1" state="CA" product="socks" sold="500"/>
<store number="1" state="CA" product="shirt" sold=""/>
<store number="2" state="CA" product="broiler" sold=""/>
<store number="2" state="CA" product="toaster" sold="100"/>
<store number="2" state="CA" product="toaster" sold="50"/>
<store number="2" state="CA" product="blender" sold=""/>
<store number="2" state="CA" product="socks" sold="10"/>
<store number="2" state="CA" product="shirt" sold=""/>
<store number="3" state="CA" product="broiler" sold=""/>
<store number="3" state="MA" product="toaster" sold="50"/>
<store number="3" state="MA" product="blender" sold="100"/>
<store number="3" state="MA" product="blender" sold="150"/>
<store number="3" state="MA" product="socks" sold=""/>
<store number="3" state="MA" product="shirt" sold="10"/>
<store number="4" state="MA" product="broiler" sold=""/>
<store number="4" state="MA" product="toaster" sold=""/>
<store number="4" state="MA" product="blender" sold=""/>
<store number="4" state="MA" product="socks" sold=""/>
<store number="4" state="MA" product="shirt" sold=""/>
</result>
7
Use Case "Try-Catch" - Queries which require to recover from
errors
This use case covers queries that require to recover from
errors.
7.1
Sample Data
Q1 and Q2 are based on a errornous version of product.xml from
Shopping Scenario Schema and Data, whereas Q3
does not require any input data. Sample data for Q1 and Q2 named
product-err.xml are shown below:
<products>
<product>
<name>broiler</name>
<category>kitchen</category>
<price>100</price>
<cost>"70"</cost>
</product>
<product>
<name>toaster</name>
<category>kitchen</category>
<price>30</price>
<cost>10</cost>
</product>
<product>
<name>blender</name>
<category>kitchen</category>
<price>50</price>
<cost>25</cost>
</product>
<product>
<name>socks</name>
<category>clothes</category>
<price>5</price>
<cost>2</cost>
</product>
<product>
<name>shirt</name>
<category>clothes</category>
<price>10</price>
<cost>3</cost>
</product>
</products>
7.2 Queries
and Results
7.2.1 Q1
Calculate the margin of every product. If an error occurs,
report a user-friendly message.
Solution in XQuery:
try {
<result>{
for $product in fn:doc("product-err.xml")//product
return
<product>{$product/name}
<margin>{$product/price - $product/cost}</margin>
</product>
}</result>
} catch * {
"An error occured, please ask your consultant for help."
}
Expected Result:
An error occured, please ask your consultant for help.
7.2.2 Q2
Report the margin in procent of every product. If an error
occurs the failure should be listed, but the query should still
continue to report the other values.
Solution in XQuery:
<result>{
for $product in fn:doc("product-err.xml")//product
return
try {
<product>{$product/name}
<margin>{$product/price div $product/cost}</margin>
</product>
} catch * {
<product>{
($product/name, "Error:", $err:code)
}</product>
}
}</result>
Expected Result:
<?xml version="1.0" encoding="UTF-8"?>
<result>
<product>
<name>broiler</name>
Error: FORG0001
</product>
<product>
<name>toaster</name>
<margin>3</margin>
</product>
<product>
<name>blender</name>
<margin>2</margin>
</product>
<product>
<name>socks</name>
<margin>2.5</margin>
</product>
<product>
<name>shirt</name>
<margin>3.3333333333333333</margin>
</product>
</result>
7.2.3 Q3
For a sequence of inputs the n-th fibonacci number has to be
calculated using a pre-defined function. The function is built to
avoid long running times and therefore rejects high values by
throwing a user-defined error. If such an error occurs during
calculation, a warning should be displayed, but the processing
should continue.
Solution in XQuery:
declare namespace foo='http://foo.com';
declare function local:fib-recur($n as xs:integer) as xs:integer? {
if ($n <0) then ()
else if ($n > 100) then
fn:error(fn:QName('http://foo.com', 'ValueToBig'), 'Value too big')
else if ($n = 0) then 0
else if ($n=1) then 1
else local:fib-recur($n - 1) + local:fib-recur($n - 2)
};
<result>{
for $x in (3,1,1030,5)
return
try{
<fib input="{$x}">{local:fib-recur($x)}</fib>
}catch foo:ValueToBig {
<fib input="{$x}">Number to big</fib>
}
}</result>
Expected Result:
<?xml version="1.0" encoding="UTF-8"?>
<result>
<fib input="3">2</fib>
<fib input="1">1</fib>
<fib input="1030">Number to big</fib>
<fib input="5">5</fib>
</result>