Question

In Sql Server 2008 how can I go from here:

Owner  Animal   Age  Height   Weight  
-----  ------   ---  ------   ------ 
Steve  Dog        8     22      60 
Steve  Cat        5     11      14 
Steve  Gerbil     2     1.5     0.3  

To here:

Owner  Dog_Age  Dog_Height  Dog_Weight  Cat_Age  Cat_Height  ...
-----  -------  ----------  ----------  -------  ----------  ...
Steve       8           22          60        5          11  ...   

So I am pivoting the Animal column, but want to generate columns for all possible combinations of animals and certain columns. No aggregate function is actually being performed. Since for my table the total number of possible combinations will be fairly large, I’d like a solution that avoids me having to explicity type out every resulting column name, but I’ll do it if I must.

I have looked at several examples of the PIVOT command, but I have not run across any that create columns from combinations like above, so I’m not sure this is possible. SQL Server is not my area of expertise.

Answer 1

If you don’t care about order of columns in the final output:

DECLARE @sql NVARCHAR(MAX);

SELECT @sql = N'';

SELECT 
    @sql = @sql + ',' + Animal + '_$c$ = MAX(CASE WHEN Animal = ''' 
          + Animal + ''' THEN $c$ END)'
FROM dbo.PetStuff
GROUP BY Animal;

SELECT @sql = 'SELECT Owner '
 + REPLACE(@sql, '$c$', 'Age')
 + REPLACE(@sql, '$c$', 'Height')
 + REPLACE(@sql, '$c$', 'Weight')
 + ' FROM dbo.PetStuff
 GROUP BY Owner;';

PRINT @sql;
-- EXEC sp_executesql @sql;

If column order matters (order by animal name then age/height/weight alphabetically), then you can put the columns in a table instead and generate the SQL with slightly more work:

DECLARE @cols TABLE(col SYSNAME);
INSERT @cols SELECT 'Age' UNION ALL SELECT 'Weight' UNION ALL SELECT 'Height';

DECLARE @sql NVARCHAR(MAX);

SELECT @sql = N'';

SELECT @sql = @sql + ',' + p.Animal + '_' + col 
  + ' = MAX(CASE WHEN Animal = ''' 
  + p.Animal + ''' THEN ' + c.col + ' END)'
FROM dbo.PetStuff AS p
CROSS APPLY @cols AS c
GROUP BY p.Animal, c.col
ORDER BY p.Animal, c.col;

SELECT @sql = 'SELECT Owner ' + @sql
 + ' FROM dbo.PetStuff
 GROUP BY Owner;';

PRINT @sql;
-- EXEC sp_executesql @sql;

Can’t really think of any way to do this without dynamic SQL.