本月第一天:$monthFirstDay = date('Y-m-01',time());
本月最后天:$monthLasttDay = date('Y-m-t',time());
上月第一天: $lastMonthFirstDay = date('Y-m-01', strtotime('-1 month'));
上月最后天: $lastMonthFinalDay = date('Y-m-t', strtotime('-1 month'));
本月第一天:$monthFirstDay = date('Y-m-01',time());
本月最后天:$monthLasttDay = date('Y-m-t',time());
上月第一天: $lastMonthFirstDay = date('Y-m-01', strtotime('-1 month'));
上月最后天: $lastMonthFinalDay = date('Y-m-t', strtotime('-1 month'));