use Time::localtime;
my $tm = localtime;
my $this_month = sprintf("%04d%02d?", $tm->year+1900, ($tm->mon)+1);
my $last_month = ($tm->mon == 0) 
                    ?  sprintf("%04d12?", $tm->year+1899)
                    : sprintf("%04d%02d?", $tm->year+1900, $tm->mon);