[sql] SQL Server dynamic PIVOT query?

I know this question is older but I was looking thru the answers and thought that I might be able to expand on the "dynamic" portion of the problem and possibly help someone out.

First and foremost I built this solution to solve a problem a couple of coworkers were having with inconstant and large data sets needing to be pivoted quickly.

This solution requires the creation of a stored procedure so if that is out of the question for your needs please stop reading now.

This procedure is going to take in the key variables of a pivot statement to dynamically create pivot statements for varying tables, column names and aggregates. The Static column is used as the group by / identity column for the pivot(this can be stripped out of the code if not necessary but is pretty common in pivot statements and was necessary to solve the original issue), the pivot column is where the end resultant column names will be generated from, and the value column is what the aggregate will be applied to. The Table parameter is the name of the table including the schema (schema.tablename) this portion of the code could use some love because it is not as clean as I would like it to be. It worked for me because my usage was not publicly facing and sql injection was not a concern. The Aggregate parameter will accept any standard sql aggregate 'AVG', 'SUM', 'MAX' etc. The code also defaults to MAX as an aggregate this is not necessary but the audience this was originally built for did not understand pivots and were typically using max as an aggregate.

Lets start with the code to create the stored procedure. This code should work in all versions of SSMS 2005 and above but I have not tested it in 2005 or 2016 but I can not see why it would not work.

create PROCEDURE [dbo].[USP_DYNAMIC_PIVOT]
    (
        @STATIC_COLUMN VARCHAR(255),
        @PIVOT_COLUMN VARCHAR(255),
        @VALUE_COLUMN VARCHAR(255),
        @TABLE VARCHAR(255),
        @AGGREGATE VARCHAR(20) = null
    )

AS


BEGIN

SET NOCOUNT ON;
declare @AVAIABLE_TO_PIVOT NVARCHAR(MAX),
        @SQLSTRING NVARCHAR(MAX),
        @PIVOT_SQL_STRING NVARCHAR(MAX),
        @TEMPVARCOLUMNS NVARCHAR(MAX),
        @TABLESQL NVARCHAR(MAX)

if isnull(@AGGREGATE,'') = '' 
    begin
        SET @AGGREGATE = 'MAX'
    end


 SET @PIVOT_SQL_STRING =    'SELECT top 1 STUFF((SELECT distinct '', '' + CAST(''[''+CONVERT(VARCHAR,'+ @PIVOT_COLUMN+')+'']''  AS VARCHAR(50)) [text()]
                            FROM '+@TABLE+'
                            WHERE ISNULL('+@PIVOT_COLUMN+','''') <> ''''
                            FOR XML PATH(''''), TYPE)
                            .value(''.'',''NVARCHAR(MAX)''),1,2,'' '') as PIVOT_VALUES
                            from '+@TABLE+' ma
                            ORDER BY ' + @PIVOT_COLUMN + ''

declare @TAB AS TABLE(COL NVARCHAR(MAX) )

INSERT INTO @TAB EXEC SP_EXECUTESQL  @PIVOT_SQL_STRING, @AVAIABLE_TO_PIVOT 

SET @AVAIABLE_TO_PIVOT = (SELECT * FROM @TAB)


SET @TEMPVARCOLUMNS = (SELECT replace(@AVAIABLE_TO_PIVOT,',',' nvarchar(255) null,') + ' nvarchar(255) null')


SET @SQLSTRING = 'DECLARE @RETURN_TABLE TABLE ('+@STATIC_COLUMN+' NVARCHAR(255) NULL,'+@TEMPVARCOLUMNS+')  
                    INSERT INTO @RETURN_TABLE('+@STATIC_COLUMN+','+@AVAIABLE_TO_PIVOT+')

                    select * from (
                    SELECT ' + @STATIC_COLUMN + ' , ' + @PIVOT_COLUMN + ', ' + @VALUE_COLUMN + ' FROM '+@TABLE+' ) a

                    PIVOT
                    (
                    '+@AGGREGATE+'('+@VALUE_COLUMN+')
                    FOR '+@PIVOT_COLUMN+' IN ('+@AVAIABLE_TO_PIVOT+')
                    ) piv

                    SELECT * FROM @RETURN_TABLE'



EXEC SP_EXECUTESQL @SQLSTRING

END

Next we will get our data ready for the example. I have taken the data example from the accepted answer with the addition of a couple of data elements to use in this proof of concept to show the varied outputs of the aggregate change.

create table temp
(
    date datetime,
    category varchar(3),
    amount money
)

insert into temp values ('1/1/2012', 'ABC', 1000.00)
insert into temp values ('1/1/2012', 'ABC', 2000.00) -- added
insert into temp values ('2/1/2012', 'DEF', 500.00)
insert into temp values ('2/1/2012', 'DEF', 1500.00) -- added
insert into temp values ('2/1/2012', 'GHI', 800.00)
insert into temp values ('2/10/2012', 'DEF', 700.00)
insert into temp values ('2/10/2012', 'DEF', 800.00) -- addded
insert into temp values ('3/1/2012', 'ABC', 1100.00)

The following examples show the varied execution statements showing the varied aggregates as a simple example. I did not opt to change the static, pivot, and value columns to keep the example simple. You should be able to just copy and paste the code to start messing with it yourself

exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','sum'
exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','max'
exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','avg'
exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','min'

This execution returns the following data sets respectively.