TSQL - User defined function that calculates the difference, in months, of two dates represented by integers using the format YYYYMM

/*

       -- Execution

       select dbo.getPeriodDiff( 201012, 201103 );

       select dbo.getPeriodDiff( 201103, 201012 );

      

*/

ALTER function [dbo].[getPeriodDiff]

(

       @PeriodID1 as int

       , @PeriodID2 as int

)

returns int

as

begin

       -- Get Date

       declare @PeriodDate1 date;

              set @PeriodDate1 = dbo.getPeriodDate( @PeriodID1 );

       declare @PeriodDate2 date;

              set @PeriodDate2 = dbo.getPeriodDate( @PeriodID2 );

      

       -- Return

       return

       (

              datediff( m, @PeriodDate1, @PeriodDate2 )

       );

end;