根据主键生成单号

/**
     * 生成单号
     * @param null $model 模型
     * @param string $key 缓存key
     * @param string $prefix 单号前缀
     * @param string $field 单号字段
     * @return bool|string
     */
    public static function GetRef($model = null,$key = '',$prefix = 'NO',$field = 'ref')
    {
        for ($i = 0; $i < 10; $i++) {
            $curDate = date('Ymd');
            $id = RedisTrait::String('get',$key);
            if(!$id){
                $id = $model->where($field,'like',$prefix.$curDate.'%')->orderBy('id','desc')->withTrashed()->count();
            }
            $id = intval($id)+1;
            $ref = $prefix.$curDate.sprintf("%06d", $id);
            if (!$model->where($field, $ref)->exists()) {
                RedisTrait::String('put',$key,$id,86400);
                return $ref;
            }
        }
        return false;
    }

//使用
Class::GetRef((new Order()),Order::CACHE_KEY_SN,'SN-','order_no');