How to get the name and value of an attribute on a node/element that is not a child

Question

Hello,
Can someone shed some wisdom on how I can compare 2 xml nodes for differences.
My main challenge is I need to use the attributes/values of 'ProductDescription' and 'Features' as 'key' to identify the same node in
another doc with the same layout, but different content.
I am having trouble getting the name of the attribute on the node, 'ProductDescription' and 'Features'.  I can only seem to get the node names, but not the attributes on the node.  I need the name, because it can be different from doc to doc, so
I can't hardcode this.
Can someone please help with how to retrieve an attribute name/value on a node that is not a child.  Here's an example of what
my xml looks like:
DECLARE
@myDoc1 xml
,@mydoc2 xml
DECLARE
@ProdID int
SET @myDoc1 ='<ProductDescription ProductID="1" ProductName="Road Bike">
<Features  featureID  = "1" featureName = "body">
  <Warranty>1 year parts and labor</Warranty>
  <Maintenance>3 year parts and labor extended maintenance is available</Maintenance>
</Features>
<features featureID = "2" featureName = "seat">
  <Warranty>1 year parts and labor</Warranty>
  <Maintenance>2 year parts and labor extended maintenance is available</Maintenance>
</Features>
</ProductDescription>
SET @myDoc2 ='<ProductDescription ProductID="1" ProductName="Road Bike">
<Features  featureID  = "1" featureName = "body">
  <Warranty>2 year parts and labor</Warranty>
  <Maintenance>3 year parts and labor extended maintenance is available</Maintenance>
</Features>
<features featureID = "2" featureName = "wheel">
  <Warranty>1 year parts and labor</Warranty>
  <Maintenance>2 year parts and labor extended maintenance is available</Maintenance>
</Features>
</ProductDescription>
I need to compare the attributes of 'ProductDescription' and 'Features' from @mydoc1 against @mydoc2 to see if they are the same based on those 2 nodes first.  If they are, then i want to show the difference in the child elements. 
This will eventually be an outer join to give me the differences betw the 2 docs based on those key values (node attributes).
I used node('//*') for the path, and value('local-name(../.)', 'varchar(50)') as element
,value('.[not(@xsi:nil = "true")]','VARCHAR(255)') AS new_value
...etc...
but that only gives me the node names, and the child elements.  It does not give me back the attribute names and values from the node itself.
Thanks in advance for your help.
cee

Answer 1

Are you looking for something like this:
DECLARE @myDoc1 xml
SET @myDoc1 ='<ProductDescription ProductID="1" ProductName="Road Bike">
<Features  featureID  = "1" featureName = "body">
  <Warranty>1 year parts and labor</Warranty>
  <Maintenance>3 year parts and labor extended maintenance is available</Maintenance>
</Features>
<Features featureID = "2" featureName = "seat">
  <Warranty>1 year parts and labor</Warranty>
  <Maintenance>2 year parts and labor extended maintenance is available</Maintenance>
</Features>
</ProductDescription>'
SELECT T.c.value('local-name(.)', 'nvarchar(50)') AS name,
       T.c.value('.', 'nvarchar(50)')  AS value
FROM   @myDoc1.nodes('ProductDescription/@*') AS T(c)
Erland Sommarskog, SQL Server MVP, [email protected]