Introduction to XQuery and eXist XQuery workshop April 2006

Whisky Case study Starting point is the Collins Gem Whisky book. Based on extracts, students construct a schema. Schema diagrammed using QSEE. XML Schema generated by QSEE. InfoPath used to build an input form based on the XML schema. Sample data entered using the InfoPath form interface. Data loaded into eXist for querying.

<?mso-infoPathSolution productVersion=" " PIVersion=" " href="file:whisky.xsn" name="urn:schemas-microsoft-com:office:infopath:whisky:" language="en- gb" solutionVersion=" " ?> 132 Glen Garioch Glengarioch Distillery, Oldemldrum, Aberdeenshire Blend true This medium-bodied whisky, with its light texture and smoky flavour, is an ideal after-dinner dram. Set in the Aberdeenshire market town of Oldmeldrum, Glengarioch was reputedly founded in the 1790's. By_Appointment Running false

Executing an XQuery eXist DB a.xql XQuery Engine parameters html Client Browser eXist: Server Get a.xql parameters servlet fetch a.xql render User clicks link

Simple XQuery xquery version "1.0"; Name Address {for $w in doc('/db/whisky/data_raw.xml')/Whisky/Distillery return {data($w/Name)} {data($w/Address)} } addressList.xql

XQuery as HTML xquery version "1.0"; Name Address {for $w in doc('/db/whisky/data_raw.xml')/Whisky/Distillery return {data($w/Name)} {data($w/Address)} } XQuery ‘variable’ xQuery header XPath expression to select nodes Xquery inside XML addressList.xql

Executing an XQuery with XSLT eXist DB a.xql XQuery Engine parameters.xml XSLT Engine html Client Browser eXist: Server Get a.xql parameters servlet fetch a.xql render User clicks link xslt

Simplest XQuery -XSLT xquery version "1.0"; declare namespace transform = " let $stylesheet := doc('/db/whisky/whisky.xslt'), $whiskySet := doc('/db/whisky/data_raw.xml') return transform:transform($whiskySet,$stylesheet,()) allWhiskys.xql

Simplest XQuery -XSLT namespace prefix Retrieve this document a FLWOR expression Comma separator allWhiskys.xql xquery version "1.0"; declare namespace transform = " let $stylesheet := doc('/db/whisky/whisky.xslt'), $whiskySet := doc('/db/whisky/data_raw.xml') return transform:transform($whiskySet,$stylesheet,())

XQuery with parameter selectWhiskys.xql xquery version=“1.0”; declare namespace transform = " declare namespace request=" let $whiskyType := request:request-parameter ("whiskyType",""), $stylesheet := doc('/db/whisky/whisky.xslt'), $whiskySet := {doc('/db/whisky/data_raw.xml')/Whisky/Distillery [WhiskyType = $whiskyType]} return transform:transform($whiskySet,$stylesheet,())

XQuery with parameter xquery version=“1.0”; declare namespace transform = " declare namespace request=" let $whiskyType := request:request-parameter ("whiskyType",""), $stylesheet := doc('/db/whisky/whisky.xslt'), $whiskySet := {doc('/db/whisky/data_raw.xml')/Whisky/Distillery [WhiskyType = $whiskyType]} return transform:transform($whiskySet,$stylesheet,()) Get the value of the request parameter with this name Create an XML node XPath filter selectWhiskys.xql

XQuery is bi-lingual XML and XQuery XML node (with a single root) h XML Sequence of nodes (,, ) XQuery construct variable value $var function evaluation – see Function list concat($var,’.xm’) for loop FLWOR if-then-else if (cond) then expression else expression Mixed expressions – need { } around XQuery to distinguish – {if.. } {$x} –if (cond) then Fred else ()

FLWOR expression FLWOR for $x in sequence let $a := expression, $b := expression where condition order by $var return expression –Returns a Sequence of nodes Compare with SQL select columns from tables where condition order by –Returns a Relation (table)

An XQuery sticky form The script here has several shifts between XML to XQuery Whole interface in one script –Equivalent to PHP + MySQL XSLT revised to process a sequence of Distillery nodes into a sequence of HTML nodes.

Tools for XQuery on stocks Use a text editor (PFE32) or Dreamweaver Use the admin interface with guest/guest login to create a directory and load all the files – including the XQuery files To run a script, just click on the script in the directory listing – this will run the script (but with no parameters – you can add these in the Browser This will show you the URL to execute it – you can then use this to link from any HTML outside the eXist database. Use the test query interface to test small bits of XQuery and XPath

eXist on your own machine Use the Java client to –load files –move, copy,rename files –edit files in situ (but no Save-as) –execute queries –backup