Hi,
Here's one way, using a map:
Algorithm:
1/ Order item by @id, then by @create-date-time descending, forming a new
sequence of item.
2/ Insert item into a map keyed by @id; because you sorted on @create-date-time
descending, more recent values will be overwritten by older ones, leaving just
the older ones.
3/ Extract the values from the map to re-form your data structure.
XQuery:
let $items := <items>
<item id="201100649049" create-date-time="2013-08-27T15:43:33"/>
<item id="201100649049" create-date-time="2013-08-28T07:35:40"/>
<item id="201100649040" create-date-time="2013-08-26T07:35:40"/>
</items>
let $ordered-item :=
for $item in $items/item
order by xs:integer($item/@id), xs:dateTime($item/@create-date-time)
descending
return $item
let $map := map:map()
let $_ := $ordered-item/map:put($map, ./@id, .)
return element items {
for $key in map:keys($map)
return map:get($map, $key)
}
Notes:
i. You can't do the map:put() in the ordering FLWOR expression, as you might
first think, since / implies document-order, which is the order of the input
expression, rather that of the ordered output expression, so you'd end up
inserting into the map in document order, not the desired sorted order.
ii. I'm not ordering the final result sequence; this technique doesn't retain
the input node order, though you could append a position attribute onto the
intermediate item node, and re-order on that, if you really need to.
iii. Casting may be necessary/unnecessary depending on whether you are using a
schema.
Ellis.
On 17 Sep 2013, at 22:03, Abhishek53 S <[email protected]> wrote:
> Hi All,
>
> Need some tricks on XPATH evaluation.
>
> I need distinct id with minimum create-data-time value.
>
> Input
>
> <items>
> <item id="201100649049" create-date-time="2013-08-27T15:43:33"/>
> <item id="201100649049" create-date-time="2013-08-28T07:35:40"/>
> <item id="201100649040" create-date-time="2013-08-26T07:35:40"/>
> </items>
>
> Output (Removed row 2)
>
> <items>
> <item id="201100649049" create-date-time="2013-08-27T15:43:33"/>
> <item id="201100649040" create-date-time="2013-08-26T07:35:40"/>
> </items>
>
> Please let me know some XPATH expression to evaluate this
>
> Something like below working for distinct id but not working for minimum
> create-date-time:(
>
> $items/item[not(@id = preceding-sibling::item/@id) ]
>
>
> Thanks
> Abhishek
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