XML/XQuery/Join

Outer join

   <source lang="xml">

File: Data.xml <order>

 <car model="A">
   <id>0001</id>
   <name language="en">name 1</name>
   <colorChoices>navy black</colorChoices>
 </car>
 <car model="B">
   <id>0002</id>
   <name language="en">name 2</name>
 </car>
 <car model="B">
   <id>0003</id>
   <name language="en">name 3</name>
 </car>
 <car model="C">
   <id>0004</id>
   <name language="en">name 4</name>
   <colorChoices>white gray</colorChoices>
   <desc>Our favorite shirt!</desc>
 </car>

</order> File: prices.xml <prices>

 <priceList effDate="2006-11-15">
   <prod id="0001">
     <price currency="USD">29.99</price>
     <discount type="CLR">10.00</discount>
   </prod>
   <prod id="0002">
     <price currency="USD">69.99</price>
   </prod>
   <prod id="0003">
     <price currency="USD">39.99</price>
     <discount type="CLR">3.99</discount>
   </prod>
 </priceList>

</prices>

File: Query.xquery for $car in doc("Data.xml")//car return <car id="{$car/id}">{

               attribute price
                  {for $price in doc("prices.xml")//prices/priceList/prod
                   where $car/id = $price/@id
                   return $price/price}
 }</car>
</source>
   
  

Three-way join in a where clause

   <source lang="xml">

File: order.xml

<order>

 <car model="A">
   <id>0001</id>
   <name language="en">name 1</name>
   <colorChoices>navy black</colorChoices>
 </car>
 <car model="B">
   <id>0002</id>
   <name language="en">name 2</name>
 </car>
 <car model="B">
   <id>0003</id>
   <name language="en">name 3</name>
 </car>

</order> File: inventory.xml <inventory id="inv0001" date="2008-12-19" loc="USA">

 <car model="A" id="0001" quantity="1" color="navy"/>
 <car model="B" id="0002" quantity="1" color="red"/>
 <car model="B" id="0003" quantity="2" color="red"/>
 <car model="C" id="0004" quantity="1" color="white"/>
 <car model="C" id="0004" quantity="1" color="gray"/>
 <car model="A" id="0001" quantity="1" color="black"/>

</inventory>

File: Query.xquery for $car in doc("inventory.xml")//car,

   $car in doc("order.xml")//car,
   $price in doc("prices.xml")//prices/priceList/prod

where $car/@id = $car/id and $car/id = $price/@id return <car id="{$car/@id}"

            name="{$car/name}"
            price="{$price/price}"/>
</source>
   
  

Two-way join in a predicate

   <source lang="xml">

File: order.xml

<order>

 <car model="A">
   <id>0001</id>
   <name language="en">name 1</name>
 </car>
 <car model="B">
   <id>0002</id>
   <name language="en">name 2</name>
 </car>
 <car model="B">
   <id>0003</id>
   <name language="en">name 3</name>
 </car>

</order> File: inventory.xml <inventory id="inv0001" date="2008-12-19" loc="USA">

 <car model="A" id="0001" quantity="1" color="navy"/>
 <car model="B" id="0002" quantity="1" color="red"/>
 <car model="B" id="0003" quantity="2" color="red"/>
 <car model="C" id="0004" quantity="1" color="white"/>
 <car model="C" id="0004" quantity="1" color="gray"/>
 <car model="A" id="0001" quantity="1" color="black"/>

</inventory>

File: Query.xquery for $car in doc("inventory.xml")//car,

   $car in doc("Data.xml")//car[id = $car/@id]

return <car id="{$car/@id}"

            name="{$car/name}"
            quan="{$car/@quantity}"/>
</source>
   
  

Two-way join in a where clause

   <source lang="xml">

File: inventory.xml <inventory id="inv0001" date="2008-12-19" loc="USA">

 <car model="A" id="0001" quantity="1" color="navy"/>
 <car model="B" id="0002" quantity="1"/>
 <car model="B" id="0003" quantity="2"/>
 <car model="C" id="0004" quantity="1" color="white"/>
 <car model="C" id="0004" quantity="1" color="gray"/>
 <car model="A" id="0001" quantity="1" color="black"/>

</inventory>

File: order.xml

<order>

 <car model="A">
   <id>0001</id>
   <name language="en">name 1</name>
 </car>
 <car model="B">
   <id>0002</id>
   <name language="en">name 2</name>
 </car>
 <car model="B">
   <id>0003</id>
   <name language="en">name 3</name>
 </car>

</order>

File: Query.xquery for $car in doc("inventory.xml")//car,

   $car in doc("Data.xml")//car

where $car/@id = $car/id return <car id="{$car/@id}"

            name="{$car/name}"
            quan="{$car/@quantity}"/>
</source>