SQL Server FOR XML Enclosing Element?

问题

Using SQL Server 2008, I have a query that emits a result set using FOR XML. Right now it is a non-compliant fragment.

How can I wrap my result XML in an enclosing element and then put a simple XML declaration on top with a single schema/namespace reference to make the output compliant?

Thanks.

回答1:

It is not possible to have the xml processing instruction in a xml datatype in sql server. See Limitations of the xml Data Type

This code

declare @XML xml =  
  '<?xml version="1.0"?>
   <root>Value</root>'

select @XML

Has the output

<root>Value</root>

You can build the xml as a string with the xml processing instruction in place.

declare @XML xml = '<root>Value</root>'
declare @XMLStr nvarchar(max) = '<?xml version="1.0"?>'

set @XMLStr = @XMLStr + cast(@XML as nvarchar(max))

select @XMLStr

Output

--------------------------------------------------------------------------
<?xml version="1.0"?><root>Value</root>

回答2:

Add "WITH XMLNAMESPACES" to the beginning and a ROOT() to the FOR XML clause:

WITH XMLNAMESPACES ( DEFAULT 'http://namespace_uri_here' )
SELECT * 
FROM TABLE
FOR XML AUTO, ROOT('TopLevel')

来源：https://stackoverflow.com/questions/5423560/sql-server-for-xml-enclosing-element