SQL Server - UNPIVOT Dinámico

CREATE TABLE `imputacion de costes` (

  `ID` varchar(255) DEFAULT NULL,

  `TRABAJADOR` varchar(255) DEFAULT NULL,

  `Salario Base` double(10,3) DEFAULT NULL,

  `BONUS` double(10,3) DEFAULT NULL,

  `A CTA CONV` double(10,3) DEFAULT NULL,

  `INCENTIVOS` double(10,3) DEFAULT NULL,

create table temp

(

    date datetime,

    category varchar(3),

    amount money

)

insert into temp values ('1/1/2012', 'ABC', 1000.00)

insert into temp values ('2/1/2012', 'DEF', 500.00)

insert into temp values ('2/1/2012', 'GHI', 800.00)

insert into temp values ('2/10/2012', 'DEF', 700.00)

insert into temp values ('3/1/2012', 'ABC', 1100.00)

DECLARE @cols AS NVARCHAR(MAX),

    @query  AS NVARCHAR(MAX);

SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.category)

            FROM temp c

            FOR XML PATH(''), TYPE

            ).value('.', 'NVARCHAR(MAX)')

        ,1,1,'')

set @query = 'SELECT date, ' + @cols + ' from

            (

                select date

                    , amount

                    , category

                from temp

           ) x

            pivot 

            (

                 max(amount)

                for category in (' + @cols + ')

            ) p '

execute sp_executesql @query

drop table temp