XPath concat with EXTRACT function Oracle - sql

Question

I want to extract the values of "KEY" and "VALUE" and concat these results using XPath with EXTRACT.
Sample XML as below.
<PivotSet>
<item>
<column name = "KEY">RET_1</column>
<column name = "VALUE">A</column>
</item>
<item>
<column name = "KEY">RET_2</column>
<column name = "VALUE">R</column>
</item>
<item>
<column name = "KEY">RET_3</column>
<column name = "VALUE">P</column>
</item>
</PivotSet>
I need to return in SQL something like
RET_1#A;RET_2#R;RET_3#P
where the delimiter '#' separates the key/value and ':' separates the items. I want to do it with EXTRACT and XPath.

Answer 1

You can use ListAgg along with an XmlTable, see below:
select LISTAGG(keyItem || '#' || keyValue, ';') WITHIN GROUP (ORDER BY keyItem) AS Concated
from XmlTable( '/PivotSet/item' PASSING XmlType('<PivotSet>
<item>
<column name = "KEY">RET_1</column>
<column name = "VALUE">A</column>
</item>
<item>
<column name = "KEY">RET_2</column>
<column name = "VALUE">R</column>
</item>
<item>
<column name = "KEY">RET_3</column>
<column name = "VALUE">P</column>
</item>
</PivotSet>') COLUMNS keyItem PATH '*:column[#name = "KEY"]',
keyValue PATH '*:column[#name = "VALUE"]');
You could use ExtractValue, but you would need to know how many //item elements are in your XML and then indicate in your path portion of the extract call, but this is a little messy IMO:
SELECT ExtractValue(xmlOut, '//item[1]/column[#name="KEY"]') || '#' || ExtractValue(xmlOut, '//item[1]/column[#name="VALUE"]') || ';' ||
ExtractValue(xmlOut, '//item[2]/column[#name="KEY"]') || '#' || ExtractValue(xmlOut, '//item[2]/column[#name="VALUE"]') || ';' ||
ExtractValue(xmlOut, '//item[3]/column[#name="KEY"]') || '#' || ExtractValue(xmlOut, '//item[3]/column[#name="VALUE"]') As Concatted
FROM
(
SELECT XmlType('<PivotSet>
<item>
<column name = "KEY">RET_1</column>
<column name = "VALUE">A</column>
</item>
<item>
<column name = "KEY">RET_2</column>
<column name = "VALUE">R</column>
</item>
<item>
<column name = "KEY">RET_3</column>
<column name = "VALUE">P</column>
</item>
</PivotSet>') as xmlOut FROM dual
);