public function discount()
{
$tbl = M("Rate");
if(IS_POST){
            
            
            if(time()> date('Y-m-01', strtotime(date("Y-m-d"))) ){
                $this->ajaxReturn(array("status"=>0,"message"=>"一个月只能设置一次"));
            }else{
     $discount = ($_POST['discount']);
     if($discount > 9 || $discount < 1){
     $this->ajaxReturn(array("status"=>0,"message"=>"折扣必须在1~9 之间."));
     }
     $rate = 5 / $discount;
     $wxid = M('MerchantNetbar')->where("mid = ".session("mid_Merchant"))->find()['wxid'];
     if($data = $tbl->where(['wxid'=>$wxid])->find()){
     $data['rate']=$rate;
     $data['discount']=$discount;
     $tbl->save($data);
     }else{
     $data = ['wxid'=>$wxid,'rate'=>$rate,'discount'=>$discount];
     $tbl->add($data);
     }
            }            

$this->ajaxReturn(array("status"=>1,"message"=>"折扣修改成功."));
}{
$rate = $tbl->join("`tp_merchant_netbar` ON `tp_merchant_netbar`.`wxid`=`tp_rate`.`wxid`")->where("mid = ".session("mid_Merchant"))->find();

$this->discount = '0'==rate['discount'] ? number_format(round((0.5 / $rate['rate'] )* 1000)/100, 1) : $rate['discount'];
            $this->display();
} }
我要在里面加一个时间的比较   要相隔一个月