Information Integration Within the Enterprise Using XML by Julie Basu & Nirav Chanchani
WSJ Vol 04 Issue 05 - pg.50

Listing 1

<catalog>
  <items>
        <item>
             <name> Item 1 </name>
             <price> 50.00  </price>
             <suppnum> S1 </suppnum>
        </item>
        <item>           
             <name> Item 2 </name>
             <price> 75.00 </price>
             <suppnum> S2 </suppnum>
        </item>
        … … … 
    </items>
</catalog>

Listing 2

for $item in document("catalog.xml")//item,
    $supplier in document("suppliers.xml")
     //supplier [suppnum=
              $item/suppnum]
    where $item/price < 100
    order by $supplier/suppname
     return
        <item>
           { $item/name,
             $supplier/suppname,
             $supplier/address,
             $item/price
           }
        </item>