How to Retrieve XML Attribute Values Using SQL: XQuery vs. XPath?

Retrieving Attribute Value from XML: SQL Techniques

In SQL, retrieving the value of an attribute from XML data can be achieved through various methods. Let's examine how to extract the language attribute value from the provided XML:

<email>
  <account language="en" ... />
</email>

XQuery Approach:

The XQuery language enables easy extraction of XML attribute values. The following query demonstrates this:

declare @xml xml =
'<email>
  <account language="en" />
</email>'

select @xml.value('(/email/account/@language)[1]', 'nvarchar(max)')

This query directly accesses the language attribute using the XQuery syntax.

XML Path (XPath) Approach:

XPath can also be used to navigate XML structures and retrieve attribute values. An example query using XPath is:

declare @t table (m xml)

insert @t values 
    ('<email><account language="en" /></email>'), 
    ('<email><account language="fr" /></email>')

select m.value('(/email/account/@language)[1]', 'nvarchar(max)')
from @t

The XPath expression identifies the account element and retrieves the language attribute value.

Both XQuery and XPath provide powerful mechanisms for extracting information from XML data. The appropriate approach depends on the specific data structure and desired results. By utilizing these techniques, you can effectively access and process XML data within your SQL queries.

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