TSQL - User defined function that converts a date into an integer with the format YYYYMM (PeriodID)

/*

       -- Execution

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

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

*/

ALTER function [dbo].[getPeriodID](

       @PeriodDate date

)

returns int

as

begin

       return(

              ( year( @PeriodDate ) * 100 )

              + month( @PeriodDate )

       );

end

;