How to query xml value inside a xml column in SQL server - sql

Question

I have something like following code inside [XMLValue] column of a table called "AlgorithmLog":
<?xml version="1.0" encoding="utf-8"?>
<AdapterInfo xmlns:i="http://www.w3.org/2001/XMLSchema-instance"
xmlns:d1p1="http://schemas.datacontract.org/2004/07/Adapters.Adapter.CloudTrader"
xmlns="http://schemas.datacontract.org/2004/07/Adapters.Adapter"
i:type="d1p1:AlgorithmStatusReport">
<SequenceNumber>0</SequenceNumber>
<TrackingGuid i:nil="true" />
<d1p1:Broker>Default</d1p1:Broker>
...
<d1p1:XMLValue><?xml version="1.0"?><int xmlns="http://schemas.microsoft.com/2003/10/Serialization/">1900</int></d1p1:XMLValue>
</AdapterInfo>
and I want to get the value "1900" inside the node <d1p1:XMLValue>
So here is my query:
WITH XMLNAMESPACES('http://schemas.datacontract.org/2004/07/Adapters.Adapter' AS x,
'http://schemas.datacontract.org/2004/07/Adapters.Adapter.CloudTrader' As p,
'http://schemas.microsoft.com/2003/10/Serialization/'as w)
SELECT
XMLValue.query('(/x:AdapterInfo/p:XMLValue/w:int)[1]')AS [XMLVaule]
FROM AlgorithmLog
But it returns nothing.
Could anyone tell me where I did wrong or how I can do it?
Thank you.

Answer 1

Since you have "encoded" XML inside another XML node, and you cannot automatically cast to the XML datatype using the .value() XQuery method, it all gets a bit involved - but this seems to work for me:
;WITH XMLNAMESPACES('http://schemas.datacontract.org/2004/07/Adapters.Adapter' AS x,
'http://schemas.datacontract.org/2004/07/Adapters.Adapter.CloudTrader' As p,
'http://schemas.microsoft.com/2003/10/Serialization/'as w)
SELECT
CAST(XmlContent.value('(/x:AdapterInfo/p:XMLValue)[1]', 'varchar(2000)') AS XML).value('(w:int)[1]', 'int') AS [XMLValue]
FROM AlgorithmLog
WHERE ....... -- use whatever condition makes sense for you here