Create XML with variable element names from a data table with values and names

Question

I wasn\'t able to find a relevant post, so I decided to ask.

I have the following table in my SQL Server database:

ID       attname    value 
-------         


        

Answer 1

This is not possible normally. SQL Server does not support variable column aliases for your output. But there are workarounds:

string concatenation

The approach is a bit ugly, as I normally would not prefer to create XML via string concatenation. But by wrapping the value with a SELECT FOR XML PATH itself, this is even stable with forbidden characters like <> or &.

DECLARE @tbl TABLE(ID BIGINT,attname NVARCHAR(100),value NVARCHAR(100));
INSERT INTO @tbl VALUES 
 (22405543,'blktradind','N') 
,(22405543,'brkref','IRVTGB2X') 
,(22405543,'buyamt','104650.2000')  
,(22405543,'buycurref','USD')  
,(22405543,'Buy53ref',NULL) 
,(22405543,'Buy56ref',NULL) 
,(22405543,'Buy57ref','IRVTBEBB');

WITH DistinctIDs AS
(
    SELECT DISTINCT ID FROM @tbl
)
SELECT ID AS [@id]
      ,(
        SELECT CAST(N'<' + attname + N'>' + ISNULL((SELECT value AS [*] FOR XML PATH('')),N'') + N'' AS XML)
        FROM @tbl AS tbl
        WHERE tbl.ID=DistinctIDs.ID
        FOR XML PATH(''),TYPE
       )
FROM DistinctIDs
FOR XML PATH('Message')

The result

  N
  IRVTGB2X
  104650.2000
  USD
  
  
  IRVTBEBB

dynamic SQL

You could build the full statement dynamically and use EXEC(@cmd) to execute it. Something like this:

(Attention!!: The SELECT TOP 1 to get the ID is not appropriate for actual data!)

DECLARE  @cmd NVARCHAR(MAX)=
(
    SELECT 'SELECT ''' + CAST((SELECT TOP 1 ID FROM @tbl) AS NVARCHAR(100)) + ''' AS [@id] ' 
    + (
    SELECT ',''' + ISNULL(value,'') + ''' AS [' + attname + ']'
    FROM  @tbl
    FOR XML PATH('')
    )
    + ' FOR XML PATH(''Message'')'
);
EXEC(@cmd)