adding encoding information to the result of FOR XML [duplicate] - sql

Question

This question already has answers here:
SQL Server FOR XML Enclosing Element?
(2 answers)
Closed 7 years ago.
I have a Script, which returns a XML using FOR XML in SQL 2008. Is there any way to add the version and encoding information in the beginning of the output. Eventually, i am planning to save the output in a file.
For example, right now my output looks like this
<Agents>
<Agent id="1">
<Name>Mike</Name>
<Location>Sanfrancisco</Location>
</Agent>
<Agent id="2">
<Name>John</Name>
<Location>NY</Location>
</Agent>
</Agents>
I would like to append the line <?xml version="1.0" encoding="UTF-8"?> in the beginning of the Xml output
So i want the output something like
<?xml version="1.0" encoding="UTF-8"?>
<Agents>
<Agent id="1">
<Name>Mike</Name>
<Location>Sanfrancisco</Location>
</Agent>
<Agent id="2">
<Name>John</Name>
<Location>NY</Location>
</Agent>

Answer 1

As #gbn points out in another answer and on another question, "the XML data is stored internally as ucs-2", and SQL Server doesn't include it when producing the data. However, you can convert the XML to a string and append the XML declaration at the beginning manually. However, simply using UTF-8 in the declaration would be inaccurate. The Unicode string which SQL produces is in UCS-2. For example, this will fail:
SELECT CONVERT(xml,N'<?xml version="1.0" encoding="UTF-8"?>' + CONVERT(NVARCHAR(MAX),CONVERT(XML,N'<x>' + NCHAR(10176) + N'</x>')));
with error:
Msg 9402, Level 16, State 1, Line 1 XML parsing: line 1, character 38,
unable to switch the encoding
This, on the other hand, will work as expected:
SELECT CONVERT(xml,N'<?xml version="1.0" encoding="UCS-2"?>' + CONVERT(NVARCHAR(MAX),CONVERT(XML,N'<x>' + NCHAR(10176) + N'</x>')));
Here is code which will produce the full, declaration-laden XML string you seek for your example data:
DECLARE #Agents TABLE
(
AgentID int,
AgentName nvarchar(50),
AgentLocation nvarchar(100)
);
INSERT INTO #Agents (AgentID, AgentName, AgentLocation) VALUES (1, N'Mike', N'Sanfrancisco');
INSERT INTO #Agents (AgentID, AgentName, AgentLocation) VALUES (2, N'John', N'NY');
WITH BaseData AS
(
SELECT
(
SELECT
AgentID AS '#id',
AgentName AS 'Name',
AgentLocation AS 'Location'
FROM #Agents
FOR XML PATH('Agent'), ROOT('Agents'), TYPE
) AS AgentXML
), FullStringTable AS
(
SELECT
*,
'<?xml version="1.0" encoding="UCS-2"?>' +
CONVERT(nvarchar(max),AgentXML) AS FullString
FROM BaseData
)
SELECT
AgentXML AS OriginalXML,
FullString,
CONVERT(xml,FullString) AS FullStringConvertedToXML
FROM FullStringTable;

Answer 2

SQL Server internally always uses utf-16 ucs-2 so you could just append it like we did. That is, SQL Server would never generate anything with "utf-8".
Edit: after some digging:
http://www.devnewsgroups.net/group/microsoft.public.sqlserver.xml/topic60022.aspx
http://forums.asp.net/t/1455808.aspx

Answer 3

If you will not be attempting to manipulate the results as TSQL XML then the simplest thing to do will be create a varchar with the string you wish to append then add the XML to it using a CAST statemnt to convert the XML to varchar.
declare #testXML as XML
declare #testPrefix as varchar(255)
set #testPrefix = '<?xml version="1.0" encoding="UTF-8"?>'
set #testXML = '<Agents> <Agent id="1"> <Name>Mike</Name> <Location>Sanfrancisco</Location> </Agent> <Agent id="2"> <Name>John</Name> <Location>NY</Location> </Agent></Agents>'
select #testPrefix
Select #testXML
select #testPrefix + CAST(#testXML as varchar(max))