SELECT FOR XML AUTO and return datatypes

Question

During playing with sys.dm_exec_describe_first_result_set I get to this point:

CREATE TABLE #tab(col INT, x XML );
INSERT INTO #tab(col,x) VALUES (1         


        

Answer 1

Interesting question! The NTEXT is really strange!

I have an idea about the sub-query: When you return an XML it is ever transfered as string, unless you specify TYPE (You surely know this from nested XML with CROSS APPLY or from string concatenation with STUFF, where you somethimes see this with TYPEand a follwing .value() - and sometimes "naked".

I could not really reproduce your results (SQL Server 2012 too). Simple copy'n'paste comes back with (I wanted to test with declared table variable and return value of a function):

Simple XML              NULL                  NULL
Wrapped with subquery   NULL                  NULL
XML column              NULL                  NULL
Casted XML              x                     xml
Wrapped Casted XML      wrapped               xml
Text value              text_string           ntext
Wrapped Text Value      text_string_wrapped   ntext

EDIT: There was a new observation I thought was unclear, but it was my mistake... Took it away...