Find element or attribute value anywhere in XML - sql

Question

I am trying to find the value of an element / attribute regardless of where it exists in the XML.
XML:
<?xml version="1.0" encoding="UTF-8"?>
<cXML payloadID="12345677-12345567" timestamp="2017-07-26T09:11:05">
<Header>
<From>
<Credential domain="1212">
<Identity>01235 </Identity>
<SharedSecret/>
</Credential>
</From>
<To>
<Credential domain="1212">
<Identity>01234</Identity>
</Credential>
</To>
<Sender>
<UserAgent/>
<Credential domain="8989">
<Identity>10678</Identity>
<SharedSecret>Testing123</SharedSecret>
</Credential>
</Sender>
</Header>
<Request deploymentMode="Prod">
<ConfirmationRequest>
<ConfirmationHeader noticeDate="2017-07-26T09:11:05" operation="update" type="detail">
<Total>
<Money>0.00</Money>
</Total>
<Shipping>
<Description>Delivery</Description>
</Shipping>
<Comments>WO# generated</Comments>
</ConfirmationHeader>
<OrderReference orderDate="2017-07-25T15:22:11" orderID="123456780000">
<DocumentReference payloadID="5678-4567"/>
</OrderReference>
<ConfirmationItem quantity="1" lineNumber="1">
<ConfirmationStatus quantity="1" type="detail">
<ItemIn quantity="1">
<ItemID>
<SupplierPartID>R954-89</SupplierPartID>
</ItemID>
<ItemDetail>
<UnitPrice>
<Money currency="USD">0.00</Money>
</UnitPrice>
<Description>Test Descritpion 1</Description>
<UnitOfMeasure>QT</UnitOfMeasure>
</ItemDetail>
</ItemIn>
</ConfirmationStatus>
</ConfirmationItem>
<ConfirmationItem quantity="1" lineNumber="2">
<ConfirmationStatus quantity="1" type="detail">
<ItemIn quantity="1">
<ItemID>
<SupplierPartID>Y954-89</SupplierPartID>
</ItemID>
<ItemDetail>
<UnitPrice>
<Money currency="USD">0.00</Money>
</UnitPrice>
<Description>Test Descritpion 2</Description>
<UnitOfMeasure>QT</UnitOfMeasure>
</ItemDetail>
</ItemIn>
</ConfirmationStatus>
</ConfirmationItem>
</ConfirmationRequest>
</Request>
</cXML>
I want to get the value of the payloadID on the DocumentReference element. This is what I have tried so far:
BEGIN
Declare #Xml xml
Set #Xml = ('..The XML From Above..' as xml)
END
--no value comes back
Select c.value('(/*/DocumentReference/#payloadID)[0]','nvarchar(max)') from #Xml.nodes('//cXML') x(c)
--no value comes back
Select c.value('#payloadID','nvarchar(max)') from #Xml.nodes('/cXML/*/DocumentReference') x(c)
--check if element exists and it does
Select #Xml.exist('//DocumentReference');
I tried this in an xPath editor: //DocumentReference/#payloadID
This does work, but I am not sure what the equivalent syntax is in SQL

Answer 1

Calling .nodes() (like suggested in comment) is an unecessary overhead...
Better try it like this:
SELECT #XML.value('(//DocumentReference/#payloadID)[1]','nvarchar(max)')
And be aware, that XPath starts counting at 1. Your example with [0] cannot work...
--no value comes back
Select c.value('(/*/DocumentReference/#payloadID)[0]','nvarchar(max)') from...