SQL Server: How to convert an XML variable to UTF-8 encoded varbinary(max)?

Question

In SQL Server the default conversion from the xml type to varbinary uses XML text encoding (start and end tags with angled brackets etc) using UTF-16 character encoding. Eg

declare @xml xml = '<foo><bar>abc</bar></foo>';
declare @foo varbinary(max);
set @foo = CONVERT(varbinary(max), @xml, 2);
select @foo

Yields:

0xFFFE3C0066006F006F003E003C006200610072003E006100620063003C002F006200610072003E003C002F0066006F006F003E00

Notice the zeros, indicating the double byte characters. Is there a way to convert into UTF-8?

Answer 1

Maybe it's not the best way to do this, but I solved this converting the xml to varchar first:

declare @xml xml = '<foo><bar>abc</bar></foo>';
declare @xmlvarchar varchar(max) = CONVERT(varchar(max), @xml)
declare @foo varbinary(max) = CONVERT(varbinary(max), @xmlvarchar);
select @foo

The output is:

0x3C666F6F3E3C6261723E6162633C2F6261723E3C2F666F6F3E

Of course, varchar depends on your database collation, in my case (non special characters) this solution works perfectly.