Comparing Xml in a Text Field

Question

We have a Text field which saves Xml data (not too big, 20 to 40 lines usually), in one of the stored procedures, we are receiving the Xml, which needs to be either inserted or updated based on whether that record already exists in table or not. We are doing
that match based on other non-xml fields but in one case we don't have any other option but to compare xml, so here is my question.
What's the most performance efficient way to compare Xml (which is passed as input parameter to SP as Text) to the one already saved in Table as Text? We are running Sql 2005.
Thanks
Syed

Answer 1

Hi Syed_Sajid,
Regarding your description, are you looking for approach to compare xml structured TEXT fields? If so, you can reference the below sample.
DECLARE @Tab TABLE(id INT, content TEXT)
INSERT INTO @Tab SELECT 1,'<catalog>
<book>
<author>Gambardella, Matthew</author>
<title>XML Developer''s Guide</title>
<genre>Computer</genre>
<price>44.95</price>
<publish_date>2000-10-01</publish_date>
<description>An in-depth look at creating applications
with XML.</description>
</book>
</catalog>'
DECLARE @XML1 XML,@XML2 XML;
SELECT @XML2= content FROM @Tab WHERE id=1
SET @XML1 = '<catalog><book>
<author>Corets, Eva</author>
<title>Maeve Ascendant</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2000-11-17</publish_date>
<description>After the collapse of a nanotechnology
society in England, the young survivors lay the
foundation for a new society.</description>
<extra>a</extra>
</book>
</catalog>'
;WITH XML1 AS
SELECT T.N.value('local-name(.)', 'nvarchar(max)') AS NodeName,
T.N.value('.', 'nvarchar(max)') AS Value
FROM @XML1.nodes('/catalog/book/*') AS T(N)
XML2 AS
SELECT T.N.value('local-name(.)', 'nvarchar(max)') AS NodeName,
T.N.value('.', 'nvarchar(max)') AS Value
FROM @XML2.nodes('/catalog/book/*') AS T(N)
SELECT ISNULL(XML1.NodeName, XML2.NodeName) AS NodeName,
XML1.Value AS Value1,
XML2.Value AS Value2
FROM XML1
FULL outer join XML2
ON XML1.NodeName = XML2.NodeName
WHERE ISNULL(XML1.Value, '') <> ISNULL(XML2.Value, '')
The different nodes between two xmls will be listed in the result above.
If you have any question, feel free to let me know.
Eric Zhang
TechNet Community Support