Tab character disappearing in value when its the only character

Question

Hi,
We have a data tier app that consumes some XML generated by another SQL Server instance. The information is passed via XML files. We noticed when loading the XML file back into an XML variable within SQL Server, any values which contain just a tab are lost.
This can be demonstrated by running this example code:
DECLARE @test1 NVARCHAR(max) = '<Delimiter> </Delimiter>', -- only a tab as the value
@test2 NVARCHAR(max) = '<Delimiter>. </Delimiter>' -- a tab with another character, in this case a .
SELECT
CAST(@test1 AS XML) AS [Example 1], -- doesn't work
CAST(@test2 AS XML) AS [Example 2], -- works
CAST(REPLACE(@test1,' ','&#009;') AS XML) AS [Example 3] -- works
The results are:
<Delimiter />
<Delimiter>. </Delimiter>
<Delimiter> </Delimiter>
Notice the first example disregarded the tab content, while the later 2 retained the tab.
Is there an option within SQL server that would enable us to retain special character values (one of which is the tab) without performing any special handling before casting to XML?
Thanks,
Jay :)
If you shake a kettle, does it boil faster?

Answer 1

Hi Elvis,
It worked. We got the source service to add xml:space="preserve", and if it came in missing, we added it before converting to XML. Any outgoing XML we used the query:
SET @xml.modify('insert attribute xml:space {"preserve"} into (/Test[1])')
To add the correct handling in. These links were also helpful in describing the handling:
http://msdn.microsoft.com/en-us/library/ms190965.aspx (White Space Handling in Typed XML)
http://technet.microsoft.com/en-us/library/ms187928(v=sql.100).aspx
Thanks for pointing in the right direction.
Cheers,
Jay :)
If you shake a kettle, does it boil faster?