Here's some code to generate the date range for the previous month. You'll want it formatted differently if using it for queries, however.

use strict;
use warnings;

my (@mon, $mon, $year);
@mon = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

($mon, $year) = (localtime(time))[4,5];

$year += 1900 if $year < 2000;
if ($mon == 0) {
    $mon = 12;
    $year--;
}
if ($mon == 2) {
    if ($year % 4 != 0) {
        $mon[1] = 28;
    }
    elsif ($year % 400 == 0) {
        $mon[1] = 29;
    }
    elsif ($year % 100 == 0) {
        $mon[1] = 28;
    }
    else {
        $mon[1] = 29;
    }
}
$year = $year % 100;

print sprintf('%02d/%02d/%02d', $mon, 1, $year),
      " through ",
      sprintf('%02d/%02d/%02d', $mon, $mon[$mon-1], $year);
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