XML/XQuery/Aggregate
Содержание
Aggregating values
<source lang="xml">
File: Data.xml <employees>
<employee name="James" salary="1234" yearServed="1" location="North"/> <employee name="Joe" salary="3211" yearServed="2" location="South"/> <employee name="Jod" salary="3422" yearServed="3" location="North"/> <employee name="Jason" salary="1321" yearServed="4" location="East"/> <employee name="Jack" salary="2324" yearServed="3" location="North"/> <employee name="Jeep" salary="4321" yearServed="2" location="East"/> <employee name="Jane" salary="2344" yearServed="1" location="South"/>
</employees> File: Query.xquery for $d in distinct-values(doc("Data.xml")//employee/@location) let $employees := doc("Data.xml")//employee[@location= $d] order by $d return <department name="{$d}" total="{sum($employees/@yearServed)}"/> Output: <?xml version="1.0" encoding="UTF-8"?> <department total="6" name="East"/> <department total="7" name="North"/> <department total="3" name="South"/>
</source>
Aggregation
<source lang="xml">
File: Data.xml <employees>
<employee name="James" salary="1234" yearServed="1" location="North"/> <employee name="Joe" salary="3211" yearServed="2" location="South"/> <employee name="Jod" salary="3422" yearServed="3" location="North"/> <employee name="Jason" salary="1321" yearServed="4" location="East"/> <employee name="Jack" salary="2324" yearServed="3" location="North"/> <employee name="Jeep" salary="4321" yearServed="2" location="East"/> <employee name="Jane" salary="2344" yearServed="1" location="South"/>
</employees> File: Query.xquery for $d in distinct-values(doc("Data.xml")//employee/@location) let $employees := doc("Data.xml")//employee[@location = $d] order by $d return <department code="{$d}"
numemployees="{count($employees)}" distinct="{count(distinct-values($employees/@yearServed))}" total="{sum($employees/@yearServed)}"/>
Output: <?xml version="1.0" encoding="UTF-8"?> <department total="6" code="East" distinct="2" numemployees="2"/> <department total="7" code="North" distinct="2" numemployees="3"/> <department total="3" code="South" distinct="2" numemployees="2"/>
</source>
Aggregation on multiple values
<source lang="xml">
File: Data.xml <employees>
<employee name="James" salary="1234" yearServed="1" location="North"/> <employee name="Joe" salary="3211" yearServed="2" location="South"/> <employee name="Jod" salary="3422" yearServed="3" location="North"/> <employee name="Jason" salary="1321" yearServed="4" location="East"/> <employee name="Jack" salary="2324" yearServed="3" location="North"/> <employee name="Jeep" salary="4321" yearServed="2" location="East"/> <employee name="Jane" salary="2344" yearServed="1" location="South"/>
</employees> File: Query.xquery let $allemployees := doc("Data.xml")//employee for $d in distinct-values($allemployees/@salary) for $n in distinct-values($allemployees[@salary = $d]/@yearServed) let $employees := $allemployees[@salary = $d and @yearServed = $n] order by $d, $n return <group salary="{$d}"
yearServed="{$n}" numemployees="{count($employees)}" total="{sum($employees/@yearServed)}"/>
Output: <?xml version="1.0" encoding="UTF-8"?> <group total="1" yearServed="1" salary="1234" numemployees="1"/> <group total="4" yearServed="4" salary="1321" numemployees="1"/> <group total="3" yearServed="3" salary="2324" numemployees="1"/> <group total="1" yearServed="1" salary="2344" numemployees="1"/> <group total="2" yearServed="2" salary="3211" numemployees="1"/> <group total="3" yearServed="3" salary="3422" numemployees="1"/> <group total="2" yearServed="2" salary="4321" numemployees="1"/>
</source>
Constraining and sorting on aggregated values
<source lang="xml">
File: Data.xml <inventory id="inv0001" date="2008-12-19" loc="USA">
<car model="A" num="0001" quantity="1" color="navy"/> <car model="B" num="0002" quantity="1" color="red"/> <car model="B" num="0003" quantity="2" color="red"/> <car model="C" num="0004" quantity="1" color="white"/> <car model="C" num="0004" quantity="1" color="gray"/> <car model="A" num="0001" quantity="1" color="black"/>
</inventory>
File: Query.xquery let $allcars := doc("Data.xml")//car for $d in distinct-values($allcars/@model) for $n in distinct-values($allcars/@num) let $cars := $allcars[@model = $d and @num = $n] where sum($cars/@quantity) > 1 order by count($cars) return if (exists($cars))
then <group model="{$d}" num="{$n}" numcars="{count($cars)}" totQuant="{sum($cars/@quantity)}"/> else ()
Output: <?xml version="1.0" encoding="UTF-8"?> <group totQuant="2" num="0003" model="B" numcars="1"/> <group totQuant="2" num="0001" model="A" numcars="2"/> <group totQuant="2" num="0004" model="C" numcars="2"/>
</source>