Question

I have a xml file like below, and i wanted to group the toyID and get the sum of how much that toy has been sold. and order it by the toyID with the highest sales.but the code that i wrote is able to sum the amount of toy sold,but the order by the highest amount of toy sold is not working.can i know which part i did wrongly?

 ToySale.XML
 <toySale companyID="1" toyID="11" >
   <amount>15</amount>
 </toySale>
 <toySale companyID="3" toyID="11" >
   <amount>12</amount>
 </toySale>
 <toySale companyID="1" toyID="22" >
   <amount>3</amount>
 </toySale>
 <toySale companyID="2" toyID="33" >
   <amount>7</amount>
 </toySale>

below is the code that i wrote:

for $t in distinct-values(ToySale.xml")//@toyID)
return <toyID>
            toyID : {$t} 

          <totalSale>{sum(for $sum in (ToySale.xml")//toySale
                     order by $sum/@toyID/../amount     
                     where $t=$sum/@toyID
                     return $sum/@productID/../amount)  }

           </totalSale

        </toyID>

Answer 1

This query:

   for $vId
     in (/*/toySale/@toyID)
                     [index-of(/*/toySale/@toyID, .)[1]]

    let $vSales := /*/toySale[@toyID eq $vId]

    order by sum($vSales/amount) descending

   return
     <sale toy-id="{$vId}" total="{sum($vSales/amount)}"/>

When applied on the provided XML document:

<toySales>
    <toySale companyID="1" toyID="11" >
        <amount>15</amount>
    </toySale>
    <toySale companyID="3" toyID="11" >
        <amount>12</amount>
    </toySale>
    <toySale companyID="1" toyID="22" >
        <amount>3</amount>
    </toySale>
    <toySale companyID="2" toyID="33" >
        <amount>7</amount>
    </toySale>
</toySales>

produces the wanted, correct result:

<sale total="27" toy-id="11"/>
<sale total="7" toy-id="33"/>
<sale total="3" toy-id="22"/>

---

An equivalent and slightly shorter query:

   for $vId in distinct-values(/*/toySale/@toyID)

     let $vSales := /*/toySale[@toyID eq $vId]

     order by sum($vSales/amount) descending

    return
       <sale toy-id="{$vId}" total="{sum($vSales/amount)}"/>