如何使用包含不带前缀的命名空间的 sp_xml_preparedocument 在 TSQL 中读取 XML？

Question

I'm running SQL Server 2019 15.0.2095.3 and I want to read the contents of an XML file to then store it into a table. The problem is that I am not receiving any errors, but the result set is empty when the XML contains a namespace without prefix, but as soon as I remove the prefixless namespace it returns data again (it does work with prefix).

Here is the code to replicate the problem:

DECLARE @idoc INT, @doc VARCHAR(1000);   
SET @doc =' 
<ROOT xmlns="http://test.com">  
<Customers>  
   <Orders>  
      <nr>5</nr>
      <line>
        <test>55</test>
        <test2>444</test2>
      </line>
   </Orders>  
</Customers>  
<Customers>  
   <Orders>    
      <nr>4</nr>
      <line>
        <test>44</test>
        <test2>444</test2>
      </line>
   </Orders>  
</Customers>  
</ROOT>';   
  
--Create an internal representation of the XML document.  
EXEC sp_xml_preparedocument @idoc OUTPUT, @doc, '<ROOT xmlns="http://test.com"/>  '
  
-- SELECT statement that uses the OPENXML rowset provider.  
    SELECT *
    FROM       OPENXML (@idoc, '/ROOT/Customers/Orders/nr' ) 

EXEC sp_xml_removedocument @idoc;  

When you remove the namespace <ROOT xmlns="http://test.com"> and just use the element without it as so: <ROOT> it will return a normal result set.

However I want the query to return the contents without changing the XML

Answer 1

Microsoft proprietary OPENXML() and its companions sp_xml_preparedocument and sp_xml_removedocument are kept just for backward compatibility with the obsolete SQL Server 2000. Their use is diminished just to very few fringe cases.

Starting from SQL Server 2005 onwards, it is strongly recommended to re-write your SQL and switch it to XQuery. Also, OPENXML() cannot take advantage of XML indexes while XQuery methods can.

SQL

DECLARE @xml XML;   
SET @xml =
N'<ROOT xmlns="http://test.com">  
<Customers>  
   <Orders>  
      <nr>5</nr>
      <line>
        <test>55</test>
        <test2>444</test2>
      </line>
   </Orders>  
</Customers>  
<Customers>  
   <Orders>    
      <nr>4</nr>
      <line>
        <test>44</test>
        <test2>444</test2>
      </line>
   </Orders>  
</Customers>  
</ROOT>';   

;WITH XMLNAMESPACES(DEFAULT 'http://test.com')
SELECT c.value('(nr/text())[1]', 'INT') AS nr
    , c.value('(line/test/text())[1]', 'INT') AS test
    , c.value('(line/test2/text())[1]', 'INT') AS test2
FROM @xml.nodes('/ROOT/Customers/Orders') AS t(c);

Output

+----+------+-------+
| nr | test | test2 |
+----+------+-------+
|  5 |   55 |   444 |
|  4 |   44 |   444 |
+----+------+-------+