EXTRACTVALUE not returning any data

Question

Hi,
While executing the below, I am getting no data. Please can you help spot the error.
The xml is as below:
<Promos xmlns:Promons="http://www.some-site.com"
xmlns="http://www.some-site.com">
<total>1</total>
<Promo>
<Line>12</Line>
<Num>IO2R1RC</Num>
</Promo>
</Promos>
The query is as below:
SELECT EXTRACTVALUE (VALUE (promos), '//total') total,
EXTRACTVALUE (VALUE (promos), '//line') line
FROM TABLE
(XMLSEQUENCE
(EXTRACT
(XMLTYPE
('<Promos xmlns:Promons="http://www.some-site.com" xmlns="http://www.some-site.com"><total>1</total><Promo><Line>12</Line><Num>IO2R1RC</Num></Promo></Promos>'
'//Promos/total'
) promos

Answer 1

Hi,
I see two issues here.
1) You have to declare all namespaces you're going to use in XPath/XQuery expressions (that's a very common gotcha).
2) You've got some XPath wrong.
See below example, assuming "v_xmldoc" is an XMLType variable holding your XML data :
SELECT EXTRACTVALUE(v_xmldoc, '/Promos/total', 'xmlns="http://www.some-site.com"') as total
     , EXTRACTVALUE(VALUE(promos), '/Promo/Line', 'xmlns="http://www.some-site.com"') as line
     , EXTRACTVALUE(VALUE(promos), '/Promo/Num', 'xmlns="http://www.some-site.com"') as num
FROM TABLE(
       XMLSEQUENCE(
         EXTRACT(
           v_xmldoc
         , '/Promos/Promo'
         , 'xmlns="http://www.some-site.com"'
     ) promos
;That example also assumes that Promo elements may occur multiple times.
Consequently, you need to break the collection into separate records, then access a specific element of a given record with EXTRACTVALUE.
Hope that helps.
Some posting tips as well :
- please always give your database version (select * from v$version), it'll help people here suggesting adequate solutions. For instance, if you're on 10.2 or above, you could use XMLTable instead.
- when pasting code snippets or tagged content, always use tags to enclose your text, it'll preserve formatting.