Extracting XML in a column from a SQL Server database - sql-server

Question

I have read dozens of posts and have tried numerous SQL queries to try and get this figured out. Sadly, I'm not a SQL expert (not even a novice) nor am I an XML expert. I understand basic queries from SQL, and understand XML tags, mostly.
I'm trying to query a database table, and have the data show a list of values from a column that contains XML. I'll give you an example of the data. I won't burden you with everything I have tried.
Here is an example of field inside of the column I need. So this is just one row, I would need to query the whole table to get all of the data I need.
When I select * from [table name] it returns hundreds of rows and when I double click in the column name of 'Document' on one row, I get the information I need.
It looks like this:
<code_set xmlns="">
<name>ExampleCodeTable</name>
<last_updated>2010-08-30T17:49:58.7919453Z</last_updated>
<code id="1" last_updated="2010-01-20T17:46:35.1658253-07:00"
start_date="1998-12-31T17:00:00-07:00"
end_date="9999-12-31T16:59:59.9999999-07:00">
<entry locale="en-US" name="T" description="Test1" />
</code>
<code id="2" last_updated="2010-01-20T17:46:35.1658253-07:00"
start_date="1998-12-31T17:00:00-07:00"
end_date="9999-12-31T16:59:59.9999999-07:00">
<entry locale="en-US" name="Z" description="Test2" />
</code>
<displayExpression>[Code] + ' - ' + [Description]</displayExpression>
<sortColumn>[Description]</sortColumn>
</code_set>
Ideally I would write it so it runs the query on the table and produces results like this:
Code Description
--------------------
(Data) (Data)
Any ideas? Is it even possible? The dozens of things I have tried that are always posted in stack, either return Nulls or fail.
Thanks for your help

Answer 1

Try something like this:
SELECT
CodeSetId = xc.value('#id', 'int'),
Description = xc.value('(entry/#description)[1]', 'varchar(50)')
FROM
dbo.YourTableNameHere
CROSS APPLY
YourXmlColumn.nodes('/code_set/code') AS XT(XC)
This basically uses the built-in XQuery to get an "in-memory" table (XT) with a single column (XC), each containing an XML fragment that represents each <code> node inside your <code_set> root node.
Once you have each of these XML fragments, you can use the .value() XQuery operator to "reach in" and grab some pieces of information from it, e.g. it's #id (attribute by the name of id), or the #description attribute on the contained <entry> subelement.

Answer 2

The following query will read the xml field in every row, then shred certain values into a tabular result set.
SELECT
-- get attribute [attribute name] from the parent node
parent.value('./#attribute name','varchar(max)') as ParentAttributeValue,
-- get the text value of the first child node
child.value('./text()', 'varchar(max)') as ChildNodeValueFromFirstChild,
-- get attribute attribute [attribute name] from the first child node
child.value('./#attribute name', 'varchar(max)') as ChildAttributeValueFromFirstChild
FROM
[table name]
CROSS APPLY
-- create a handle named parent that references that <parent node> in each row
[xml field name].nodes('//xpath to parent name') AS ParentName(parent)
CROSS APPLY
-- create a handle named child that references first <child node> in each row
parent.nodes('(xpath from parent/to child)[0]') AS FirstChildNode(child)
GO
Please provide the exact values you want to shred from the XML for a more precise answer.