How to add xml encoding <?xml version=“1.0” encoding=“UTF-8”?> to xml Output in SQL Server

Question

Probably a duplicate of unanswered. SQL Server 2008 - Add XML Declaration to XML Output

Please let me know if this is possible. I read in some blogs

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Answer 1

The accepted answer of "add it manually", while technically correct, is incomplete and hence misleading. Simply adding the XML declaration with whatever "encoding" you want doesn't change the actual encoding of the string. This is sometimes ok. If you specify "UTF-8" and convert the XML data to VARCHAR, then as long as all of the characters are standard ASCII characters (values 1 - 127), then sure, it's UTF-8 (at least there is no noticeable difference). BUT, if there are any characters with values 128 or above, then you do not have a UTF-8 encoded XML document. And if you convert the XML data to NVARCHAR, then you have a UTF-16 encoded document, regardless of what you manually specify in the XML declaration. You should only be specifying an encoding IF it is the actual encoding being used.

And until SQL Server 2019 (currently in beta at CTP 2.1), there was no way to get the encoding to be UTF-8 within SQL Server, at least not without using SQLCLR. But in SQL Server 2019, you can now convert the XML to actual UTF-8:

DECLARE @XML XML;
SET @XML = N'';
SELECT @XML,
       CONVERT(VARBINARY(100), CONVERT(NVARCHAR(MAX), @XML)), -- UTF-16 / UCS-2
       CONVERT(VARBINARY(100),
               CONVERT(VARCHAR(MAX),
                       CONVERT(NVARCHAR(MAX), @XML) COLLATE Latin1_General_100_CI_AS_SC_UTF8)
              ); -- UTF-8

That returns:

Column 1: