$yesterday_zero = strtotime(date('Y-m-d')) - 3600 * 24;
$yesterday_now = strtotime('-1 day');
$week_this_monday = strtotime('last Monday');
$tomorrow = strtotime("+1 day");
$week_last_monday = strtotime('last Monday') - 3600 * 24 * 7;
$week_last_sunday = strtotime('last Monday') - 3600 * 24;
$month_first = strtotime(date("Y") . "-" . date("m") . "-1");
$month_last = strtotime(date("Y") . "-" . date("m") . "-" . date("t"));
echo date('Y-m-01', strtotime('-1 month'));
echo "<br/>";
echo date('Y-m-t', strtotime('-1 month'));