Re: Grouping by key

Hi,

Geert wrote:
>>Are you trying to display the sum of all colno 3 elements? try 
'sum(//*[@colno=3])' instead.
>>
>>If you want the cumulative of the 'above', you could try '*[@colno = 3] 
+ sum(preceding-sibling::account/*[@colno=3])'..

Thanks Geert.  Your suggestions work but what I want to do is sum up that 
column values matching the key.  Like when I am grouping the documents by 
Town, I want to sum up the 3rd column for that town.  Please check my xml 
document format and required output format.

Asssuming my xml document is 

<documents>
<account>
<accountnumber colno="0">0001</accountnumber>
<companyname colno="1">ABC Ltd</companyname>
<town colno="2">Ford</town>
<ordervalue colno="3">115.49</ordervalue>
<postcode colno="4">FD13QG</postcode>
</account>
<account>
<accountnumber colno="0">0002</accountnumber>
<companyname colno="1">XYZ Ltd</companyname>
<town colno="2">Ford</town>
<ordervalue colno="3">120.49</ordervalue>
<postcode colno="4">XY13QG</postcode>
</account>
<account>
<accountnumber colno="0">0003</accountnumber>
<companyname colno="1">HAM Ltd</companyname>
<town colno="2">Hamtown</town>
<ordervalue colno="3">110.34</ordervalue>
<postcode colno="4">HA13QG</postcode>
</account>
</documents>

I want an output like

Ford                            235.98 
        0001    ABC Ltd 115.49  FD13QG
        0002    XYZ Ltd         120.49  XY13QG

Hamtown                 110.34
        0003    HAM Ltd 110.34  HA13QG

Thanks.