TSQL - Get dayID, a date in the format YYYYMMDD

/*

       -- Execution

       select dbo.getDayID( '1/31/2012' );

       select dbo.getDayID( cast('1/31/2012' as date) );

*/

ALTER function [dbo].[getDayID](

       @PeriodDate date

)

returns bigint

as

begin

       return(

              ( year( @PeriodDate ) * 10000 )

              + ( month( @PeriodDate ) * 100 )

              + day(@PeriodDate)

       );

end

;