$time = time();
        $dir_path = public_path('orderlog');
        if (!is_dir($dir_path))
            mkdir($dir_path, 0777, true);
        // 文件名
        $fileName = date('Ymd') . '.csv';
        //  检测文件是否已存在
        if (file_exists($dir_path . '/' . $fileName))
            unlink($dir_path . '/' . $fileName);
        // 打开文件
        $myfile = fopen($dir_path . '/' . $fileName, "w") or die("Unable to open file!");

        $title = ['日志ID', '订单号',  '用户名', '标题', '内容', '添加时间'];
        $head = mb_convert_encoding($title, 'GBK', 'utf-8');
        fwrite($myfile, $head);
        $rows = DB::table('order_log');
        $this->output->progressStart($rows->count());
        $rows->chunkById(1000, function($items) use (&$myfile) {
            foreach ($items as $item) {
                $this->output->progressAdvance();
                $data = [
                    $item->log_id,$item->order_md5,$item->username,$item->title,$item->content,date('Y-m-d', $item->add_time)
                ];
                fputcsv($myfile, $data);
            }
        }, 'log_id');

        $this->output->progressFinish();
        $endTime = time();
        $t = round(($endTime - $time) / 60);
        $this->info("共耗时：".$t."分钟");