Extracting child node value from XML using T-SQL - sql

Question

I'm stuck on trying to get the 'availability' node's value out of an envelope returned via T-SQL from a Microsoft Lync database. The usual methods of .value('(/MyElement/Something)[1]') doesn't seem to work for me.
<state xsi:type="aggregateState" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/2006/09/sip/state">
<availability>3500
</availability>
<delimiter xmlns="http://schemas.microsoft.com/2006/09/sip/commontypes" />
<timeZoneBias>-60
</timeZoneBias>
<timeZoneName>GMT Daylight Time
</timeZoneName>
<timeZoneAbbreviation>GMT Daylight Time
</timeZoneAbbreviation>
<device>computer
</device>
<end xmlns="http://schemas.microsoft.com/2006/09/sip/commontypes" />
</state>
This is the query I've been experimenting with:
SELECT TOP 1
CAST(SUBSTRING(i.Data, 0, 4000) as XML).value('(/state//availability)[1]', 'varchar(256)')
FROM dbo.PublishedCategoryInstanceView AS i
INNER JOIN dbo.CategoryDef AS d
ON (d.CategoryId = i.CategoryId)
WHERE i.PublisherId = (SELECT ResourceId FROM dbo.Resource
WHERE UserAtHost = 'my.email#mydomain.local')
ORDER BY i.LastPubTime DESC
All I get back is 'NULL' unless I do CAST(SUBSTRING(i.Data, 0, 4000) as XML).value('(/)[1]', 'varchar(256)') which returns 3500-60GMT Daylight TimeGMT Daylight Timecomputer
I do know that when I strip out the three attributes on the state element I can perform normal XML queries against the data so I can get around this by manipulating the string with a few replace statements but I'd rather learn exactly what I'm doing wrong here, if anyone can help?

Answer 1

You're just plain ignoring the XML namespace that exists on your XML root node:
<state xsi:type="aggregateState"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://schemas.microsoft.com/2006/09/sip/state">
******************************************************
You need to include that in your T-SQL query!
Try something like this:
;WITH XMLNAMESPACES(DEFAULT 'http://schemas.microsoft.com/2006/09/sip/state')
SELECT TOP 1
CAST(SUBSTRING(i.Data, 0, 4000) as XML).value('(/state//availability)[1]', 'varchar(256)')
FROM
dbo.PublishedCategoryInstanceView AS i