TSQL - User defined function that turns a YYYYMM integer, to an actual date type

This will return the date using the first day of the given month.

/*

       -- Execution

       select dbo.getPeriodDate( 201101 );

       -- Bad execution

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

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

*/

ALTER function [dbo].[getPeriodDate](

       @PeriodID int

)

returns date

as

begin

       return(

              CAST(

                     cast( cast( @PeriodID % 100 as tinyint ) as varchar(2) )

                     + '/1/'

                     +  CAST( cast( @PeriodID / 100 as int ) as varchar(4) )

                     as date

              )

       );

end

;