Distinct-values() in XQuery

Question

According Q4, 1.1.9.4 in XML Query User Case and Oracle magazine (May2003), the function should be all right. Why the following XQuery can not be excuted in command line?
Error message:
XQE: unknown function 'distinct-values'
Thanks a lot!
<dataroot>
let $a := document("Orders.xml")/dataroot/Orders
for $o in distinct-values($a/CusomerID),
$c in document("Customers.xml")/dataroot/Customers
where $c/CustomerID = $o/CustomerID
return
<Customer>
{ $c/CustomerID }
{ $c/CustomerName }
</Customer>
</dataroot>

Answer 1

Hi,
Please let me know where It went wrong.The function's return value is declared as a string but you're actually returning sequences of string literals.
One way to achieve that is using string-join function :
(here for testing purpose, I used an external $doc variable)
declare namespace xf = "http://tempuri.org/abcorg/Transformations/Distinct_Fruits/";
declare default element namespace "http://www.abc.org.com/FormDetails";
declare function xf:Distinct_Fruits( $fruits as element(Fruits)* )
as xs:string
string-join(
   for $d in distinct-values($fruits/fruit/@name)
   return concat($d, " = ", $fruits/fruit[@name=$d][1]/@color)
, "|"
xf:Distinct_Fruits($doc/Main/Fruits)Note that I assumed that a fruit with a given name will always have the same color.
If that's not the case and you might have something like :
<Main>
<abcd first="1" second="2"/>
<Fruits>
  <fruit name="banana" color="green"/>
  <fruit name="apple" color="red"/>
  <fruit name="grape" color="green"/>
  <fruit name="apple" color="red"/>
  <!-- here is a red banana! -->
  <fruit name="banana" color="red"/>
  <fruit name="apple" color="red"/>
  <fruit name="grape" color="green"/>
  <fruit name="orange" color="orange"/>
  <fruit name ="lemon" color="yellow"/>
</Fruits>
</Main>then the solution is to use deep-equal function to test if two nodes are identical (as per their values, attributes and children) :
declare function xf:Distinct_Fruits( $fruits as element(Fruits) )
as xs:string
string-join(
   for $i in $fruits/fruit
   let $f := $i[not(some $x in $i/preceding-sibling::fruit satisfies fn:deep-equal($x,.))]
   where ($f)
   return concat($f/@name, " = ", $f/@color)
, "|"
};which gives :
banana = green|apple = red|grape = green|banana = red|orange = orange|lemon = yellowEdited by: odie_63 on 12 juil. 2011 14:43 - changed first example to reflect sample modification