Retrieving an XML node value with TSQL? - sql-server

Question

What am I not getting here? I can't get any return except NULL...
DECLARE #xml xml
SELECT #xml = '<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<SOAP-ENV:Body>
<webregdataResponse>
<result>0</result>
<regData />
<errorFlag>99</errorFlag>
<errorResult>Not Processed</errorResult>
</webregdataResponse>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>'
DECLARE #nodeVal int
SELECT #nodeVal = #xml.value('(errorFlag)[1]', 'int')
SELECT #nodeVal

Answer 1

Here is the solution:
DECLARE #xml xml
SELECT #xml = '<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<SOAP-ENV:Body>
<webregdataResponse>
<result>0</result>
<regData />
<errorFlag>99</errorFlag>
<errorResult>Not Processed</errorResult>
</webregdataResponse>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>'
declare #table table (data xml);
insert into #table values (#xml);
WITH xmlnamespaces (
'http://schemas.xmlsoap.org/soap/envelope/' as [soap])
SELECT Data.value('(/soap:Envelope/soap:Body/webregdataResponse/errorFlag)[1]','int') AS ErrorFlag
FROM #Table ;
Running the above SQL will return 99.
Snapshot of the result is given below,

Answer 2

That's because errorFlag is not the root element of your XML document. You can either specify full path from root element to errorFlag, for example* :
SELECT #nodeVal = #xml.value('(/*/*/*/errorFlag)[1]', 'int')
or you can use descendant-or-self axis (//) to get element by name regardless of it's location in the XML document, for example :
SELECT #nodeVal = #xml.value('(//errorFlag)[1]', 'int')
*: I'm using * instead of actual element name just to simplify the expression. You can also use actual element names along with the namespaces, like demonstrated in the other answer.