-- Queries related to lecture on November 15, 2011

To use these examples, either install eXist (and enable its examples), or go to the XQuery sandbox (only available within ITU):

http://exist.itu.dk:8080/exist/sandbox/sandbox.xql

XML files used can be found at:

http://itu.dk/people/pagh/idb11/exml/


doc("acm-small.xml")

doc("acm-small.xml")//node[@label="Arrays"]

doc("acm-small.xml")//node[@label="Arrays"]/..

doc("acm-small.xml")//node[@label="Arrays"]/ancestor::*

doc("acm-small.xml")//node[@label="Arrays"]/ancestor::node

doc("acm-small.xml")//node[@label="Arrays"]/ancestor::node/@label/string()

doc("acm-small.xml")//node[@label="Arrays"]/../*/@label/string()


-- Show titles:
declare default element namespace "http://www.brics.dk/ixwt/recipes";
doc("recipes.xml")//title

-- Show ingredient names:
declare default element namespace "http://www.brics.dk/ixwt/recipes";
doc("recipes.xml")//ingredient/@name
-- Note: The computed result is not shown in the eXist web interface because it is not XML (no enclosing tag for attributes).

-- Show ingredient name strings:
declare default element namespace "http://www.brics.dk/ixwt/recipes";
doc("recipes.xml")//ingredient/@name/string()

- Show ingredient number 40:
declare default element namespace "http://www.brics.dk/ixwt/recipes";
(doc("recipes.xml")//ingredient)[40]/@name/string()

-- Count ingredients:
declare default element namespace "http://www.brics.dk/ixwt/recipes";
for $r in doc("recipes.xml")//recipe
    return <a>{$r/title}<numrecipes>{fn:count($r//ingredient)}</numrecipes></a>

-- Count "basic" ingredients that do not have ingredients 
declare default element namespace "http://www.brics.dk/ixwt/recipes";
for $r in doc("recipes.xml")//recipe
    return <a>{$r/title}<numrecipes>{fn:count($r//ingredient[fn:not(ingredient)])}</numrecipes></a>



Working with XML in MySQL

Note: ExtractValue() returns only CDATA, and does not return any tags that might be contained within a matching tag, nor any of their content.

select id,ExtractValue(descr,'//rcp:title') from recipelist;

select id,ExtractValue(descr,'//rcp:step[1]') from recipelist;