1. Session IV Chapter 16 – XQuery http://www.profburnett.com
CMP 051 XML Introduction
Session IV
Chapter 16 – XQuery

2. Outline XQuery Introduction XQuery Functions
Composing and XQuery Document
Identifying a Source Document
Using Path Expressions
FLWOR Expression
XQuery Syntax
XQuery Functions
Add
Select
Conditional Expressions
User Defined Functions
Joining Data Sources
XQuery and Databases
8/1/2014
Copyright © Carl M. Burnett

3. XQuery Introduction XQuery is to XML what SQL is to database tables.
XQuery is designed to query XML data
Extract information to use in a Web Service
Generate summary reports
Transform XML data to XHTML
Search Web documents for relevant information
8/1/2014
Copyright © Carl M. Burnett

4. Composing and XQuery Document
xquery version "3.0";
declare namespace ext="
"Hello World!"
xquery version "3.0";
declare namespace ext="
"Everyone count down:",
reverse(1 to 10),
"Blastoff!"
xquery version "3.0";
declare namespace ext="
<countdown>{reverse(1 to 10)}</countdown>
8/1/2014
Copyright © Carl M. Burnett

5. Identifying a Source Document
xquery version "3.0";
declare namespace ext="
doc ("C:\Student_Exercises\Session_2_Exercise_1\2016_Female_Songs_of_the_Year.xml")
8/1/2014
Copyright © Carl M. Burnett

6. Using Path Expressions
xquery version "3.0";
declare namespace ext="
doc ("C:\Student_Exercises\Session_2_Exercise_1\2016_Female_Songs_of_the_Year.xml")
/DocumentElement/Song
8/1/2014
Copyright © Carl M. Burnett

7. FLWOR Expression FLWOR - "For, Let, Where, Order by, Return".
“for” clause selects elements into a variable called $x.
“where” clause selects only elements with a specified.
“order” clause defines the sort-order.
“return” clause specifies what should be returned.
8/1/2014
Copyright © Carl M. Burnett

8. FLWOR Expression 8/1/2014 Copyright © Carl M. Burnett
2016_Female_Songs_of_the_Year.xml
xquery version "3.0";
declare namespace ext="
for $album_song in
("C:\Student_Exercises\Session_2_Exercise_1\2016_Female_Songs_of_the_Year.xml") /DocumentElement/Song
let
$songt := $album_song /Track_Name
where
contains ($album_song /Artist_Name, "Birdy")
order by
$album_song /Album_Name
return
8/1/2014
Copyright © Carl M. Burnett

9. XQuery Syntax XQuery is case-sensitive
XQuery elements, attributes, and variables must be valid XML names
An XQuery string value can be in single or double quotes
An XQuery variable is defined with a $ followed by a name, e.g. $bookstore
XQuery comments are delimited by (: and :), e.g. (: XQuery Comment :)
8/1/2014
Copyright © Carl M. Burnett

10. XQuery Functions XQuery Conditional Expressions XQuery Comparisons
1. General comparisons: =, !=, <, <=, >, >=
2. Value comparisons: eq, ne, lt, le, gt, ge
for $x in doc("books.xml")/bookstore/book
return if
then <child>{data($x/title)}</child>
else <adult>{data($x/title)}</adult>
> 10
gt 10
XQuery Functions
8/1/2014
Copyright © Carl M. Burnett

11. Joining Data Sources xquery version "1.0"; for $wndr in
doc("wonders-master.xml")/ancient_wonders/wonder
for $quake in doc("earthquake_data.xml")/earthquakes/occurrence
where $quake[cities_affected/city = $wndr/location]
return data($quake/date))
8/1/2014
Copyright © Carl M. Burnett

12. XQuery and Databases xquery version "1.0";
let $cntry_medals := collection("olympics.medals")/*
let $total_gold := sum(data($cntry_medals/gold))
let $total_silver := sum(data($cntry_medals/silver))
let $total_bronze := sum(data($cntry_medals/bronze))
let $total_medals := $total_gold + $total_silver + $total_bronze
return (
"Total gold medals awarded:", $total_gold,
"Total silver medals awarded:", $total_silver,
"Total bronze medals awarded:", $total_bronze,
"Total medals awarded:", $total_medals )
8/1/2014
Copyright © Carl M. Burnett

13. Student Exercise 1
Create a XQuery for the 2016 Female Songs of the Year.xml file using Altova XMLSpy.
Preview Transformed XQuery Output.XML file in browser.
Link XQuery files to your webpage.
FLOWR Xquery (.xqu) File
XQuery Output.XML file
Post to live server.
Preview on live site.
8/1/2014
Copyright © Carl M. Burnett

14. Review XQuery Introduction XQuery Functions
Composing and XQuery Document
Identifying a Source Document
Using Path Expressions
FLWOR Expression
XQuery Syntax
XQuery Functions
Add
Select
Conditional Expressions
User Defined Functions
Joining Data Sources
XQuery and Databases
Next – Chapter 14 - XSLT 2.0
8/1/2014
Copyright © Carl M. Burnett