Question

I am looking at whether it is possible to execute arbitrary SQL commands (dynamic SQL statements or stored procedures) and return the result as XML, in an Azure SQL Database.

I know it can be done with regular, on premises SQL Server database – in our case we use a CLR function. Alternatives ‘regular’ solutions include using OPENROWSET or OPENQUERY, neither of which is available for Azure.

A new EXECUTE … AS FOR XML option is available as of SQL Server 2012, but when I try it I get an error – I am unable to locate correct examples of its use.

exec ('select ''A'', 2, ''d''')
with result sets (as for xml)

returns

Msg 11537, Level 16, State 1, Line 1
EXECUTE statement failed because its WITH RESULT SETS clause specified 1 column(s) for result set number 1, but the statement sent 3 column(s) at run time.

To be explicitly clear; I can’t control the command being passed – it is most likely a stored procedure, and it most likely returns a single ‘regular’ (i.e. non-xml) resultset. The use case for this is in a set of SQL tests, not the actual production code.

Answer 1

I tracked down an authoritative answer from Steve Howard, Sr. Program Manager with Microsoft on the Customer Advisory Team:

AS FOR XML will not convert non-XML tabular results from
the executed statement or stored procedure into XML.
AS FOR XML specifies that the XML results from the statement or stored
procedure called by the EXECUTE statement will be converted into the
format as if they were produced by a SELECT … FOR XML … statement. All
formatting from the type directives in the original statement will be
removed, and the results returned will be as if no type directive was
specified.

But he also provided me with this alternative:

/*
       Demo of how to display results from a stored procedure in XML
       Author: Steve Howard
       Date: June 21, 2012
       Intended as a demo only. Adapt to your purposes

*/

-- for this demo, declare a variable @tsql_batch to hold the batch to be executed
-- note that this could become a parameter in a stored procedure if this is how this is used

declare @tsql_batch  nvarchar(4000)

-- set the variable for the demo only
-- you will need to set this in your testing

set @tsql_batch = N'exec forDemo'

-- declare a table to hold the results of sp_describe_first_result_set
-- note that this can also be used for multiple result sets. See the documentation
-- at: http://technet.microsoft.com/en-us/library/ff878602(v=sql.110).aspx
declare @resultDescription table
(
       is_hidden                                       bit                        null
,      column_ordinal                                  int                        not null primary key
,      name                                            sysname                    not null
,      is_nullable                                     bit                        null
,      system_type_id                                  int                        null
,      system_type_name                         nvarchar(256) null
,      max_length                                      smallint             null
,      precision                                       tinyint                    null
,      scale                                           tinyint                    null
,      collation_name                                  sysname                    null
,      user_type_id                             int                        null
,      user_type_database                       sysname                    null
,      user_type_schema                         sysname                    null
,      user_type_name                                  sysname                    null
,      assembly_qualified_type_name      nvarchar(4000)       null
,      xml_collection_id                        int                        null
,      xml_collection_database                  sysname                    null
,      xml_collection_schema                    sysname                    null
,      xml_collection_name                      sysname                    null
,      is_xml_document                                 bit                        null
,      is_case_sensitive                        bit                        null
,      is_fixed_length_clr_type          bit                        null
,      source_server                            sysname                    null
,      source_database                                 sysname                    null
,      source_schema                            sysname                    null
,      source_table                             sysname                    null
,      source_column                            sysname                    null
,      is_identity_column                       bit                        null
,      is_part_of_unique_key                    bit                        null
,      is_updateable                            bit                        null
,      is_computed_column                       bit                        null
,      is_sparse_column_set              bit                        null
,      ordinal_in_order_by_list          smallint             null
,      order_by_list_length              smallint             null
,      order_by_is_descending                   smallint             null
,      tds_type_id                                     int                        null
,      tds_length                                      int                        null
,      tcs_collation_id                         int                        null
,      tds_collation_sort_id                    tinyint                    null
)

-- populate the table variable
insert into @resultDescription
       exec sp_describe_first_result_set @tsql_batch

-- declare the cursor to create the "create table statement:
declare crs cursor for SELECT '[' + name + '] ' + system_type_name + ' ' + case is_nullable when 0 then 'not null ' else 'null ' end + '
' FROM @resultDescription order by column_ordinal asc

-- variables to hold the statement to be executes as well as the current value from the cursor
declare @exec NVARCHAR(4000)
declare @curVal      nvarchar(1000)
open crs
fetch next from crs into @curval
-- begin building the dynamic SQL statement to be executed
set @exec = 'DECLARE @temp TABLE 
(
' + @curval

fetch next from crs into @curval

while @@FETCH_STATUS = 0
begin
       set @exec = @exec + ', ' + @curVal
       fetch next from crs into @curVal
end
close crs
deallocate crs
set @exec = @exec + '
)


INSERT INTO @temp
       exec sp_executesql N''' + @tsql_batch + '''

SELECT * FROM @temp FOR XML AUTO

' 


-- get the results
exec (@exec)


-- of you want to just see the statement that was executed:

print @exec