Simplify Dynamic SQL Pivot Table

Question

I have written a Dynamic Pivot Table Query based on the following. Here is a SQL FIDDLE for reference.

CREATE TABLE TestTable1 ([idnumber] INT, [DataTypeId]         


        

Answer 1

You can shorten your code considerably. First, you can just use count to aggregate the data in the PIVOT. There is no need for the inner count to aggregate the data or the HAVING clause. Finally, you only need to create the list of columns once. You could easily improve the code to:

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT ',' + QUOTENAME(DataTypeId) 
                    from TestTable1
                    group by DataTypeId
                    order by DataTypeId
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query 
      = N'SELECT idnumber, ' + @cols + N' 
          from 
          (
            select idnumber, DataTypeId
            from TestTable1
          ) x
          pivot 
          (
            count(DataTypeId)
            for DataTypeId in (' + @cols + N')
          ) p '

exec sp_executesql @query;

See SQL Fiddle with Demo. This gives the same result:

| IDNUMBER | 108 | 109 | 110 | 111 |
|----------|-----|-----|-----|-----|
|        1 |   3 |   2 |   1 |   1 |
|        2 |   2 |   0 |   1 |   0 |
|        3 |   1 |   0 |   0 |   0 |
|        4 |   2 |   0 |   1 |   1 |