Calculate age - Most easiest way

create function [dbo].[fn_calc_age] (@dob datetime)
returns varchar(64)
as
begin

declare @age int
declare @getdate datetime = getdate()
    
    if @dob >= @getdate
        return 'Invalid Input'

    set @age = datediff(yy, @dob, @getdate)

    if month(@dob) > month(@getdate) or
      (month(@dob) = month(@getdate) and
       day(@dob)   > day(@getdate))
        set @age = @age - 1

    return convert(varchar,@age) + ' Years and ' + convert(varchar,datediff(dd,dateadd(yy,@age,@dob),@getdate)) + ' Days'
end
go