SQL Multiple Item Update Using XML

From time to time, I run into a situation where I need to update multiple rows on a table. I could make multiple requests to the database, but that is rather chatty. Alternatively, a comma delimited string of values could be parsed and used to get the update. Being a big fan of XQuery, I was able to pass in an xml document and load a table that could be used to join with the table to be updated. This should scale beautifully since it plays to SQL's strengths. I have looked for a way to get some metrics on the efficiency of this verses other options and could not find a way.

This is the function I used to generate XML string. I think there are ways that I can make the function a little tighter, but it does the job and is too inefficient.

public static string BuildXmlString<t>(string xmlRootName, T[] values)
{
    StringBuilder xmlString = new StringBuilder();

    xmlString.AppendFormat("<{0}>", xmlRootName);
    int count = values.Length;
    for (int idx = 0; idx < count; idx++)
    {
        xmlString.AppendFormat("<value>{0}</value>", values[idx]);
    }
    xmlString.AppendFormat("</{0}>", xmlRootName);

    return xmlString.ToString();
}

Here is the SQL that uses the XML and updates a table with a resolved parameter value.

DECLARE @status varchar(50), @demoItemIDs xml
 SET @status = ''
 
 -- Load up the table variable with the parsed XML data
 DECLARE @DemoItems TABLE (ID int) 
 INSERT INTO @DemoItems (ID) SELECT ParamValues.ID.value('.','int')
 FROM @demoItemIDs.nodes('/demoItemIDs/value') as ParamValues(ID) 

 -- Resolve status name to ID
 DECLARE @statusID int 
 SELECT TOP 1 @statusID = DemoStatusID FROM DemoStatuses ds WHERE ds.Name = @status

 IF (@statusID > 0)
 BEGIN 
  -- Update the payments with the new status
  UPDATE [Demo].[dbo].[DemoItemApprovals]
     SET DemoStatusID = @statusID
   WHERE DemoItemID IN (
    SELECT ID FROM @DemoItems d
      INNER JOIN DemoItemApprovals da
    ON    da.PaymentID = d.ID
   )
 END
 ELSE
 BEGIN
  RAISERROR (
   N'The status ''%s'' does not exist.' -- Message text.
   , 10 -- Severity,
   , 1 -- State,
   , @status -- First argument.
   );
 END