php 处理大数据导出csv文件

        //处理csv
        $fileName = "拼团订单明细";
        $header = [
            '拼团主单号',
            '拼团子单号',
            '子订单号',
            '支付时间',
            '交易流水号',
            '商品SKU',
            '商品名称',
            '规格',
            '数量',
            '金额',
            '下单用户id',
            '下单用户昵称',
            '团长id',
            '团长昵称',
            '拼团订单状态',
            '销售订单状态',

        ];  //表头信息
        $fields = [
            'groupon_no',
            'groupon_child_no',
            'parcel_number',
            'pay_time',
            'pay_transaction_id',
            'sku_id',
            'good_name',
            'specification',
            'buy_goods_num',
            'pay_amt_e2',
            'buyer_id',
            'buyer_name',
            'groupon_author_id',
            'groupon_author_name',
            'buyer_status',
            'sell_order_status',
        ];
        //设置header
        $header = array_combine($fields,$header);
        BaseFormModel::csvExport($data, $header, [], $fileName, true, 'utf-8');
/**
     * 导出csv
     * @param array $data 数据
     * @param array $headers csv标题+数据
     * @param array $specHeaders 需要转成字符串的数组下标
     * @param string $fileName 文件名称
     * @param bool $isFirst 是否只去第一条
     * @param string $fontType 需要导出的字符集 csv默认为utf-8
     * @author zhaohao
     * @date 2019-12-10 11:38
     */
    public static function csvExport(array $data, array $headers, $specHeaders = [], $fileName = '', $isFirst = false, $fontType = 'gbk//IGNORE')
    {
        //终端导出无需header头
        header('Content-Type: application/vnd.ms-excel');
        header('Content-Disposition: attachment;filename="' . $fileName . '.csv"');
        header('Cache-Control: max-age=0');
        $fp = fopen('php://output', 'a');
        foreach ($headers as $key => $value) {
            $headers[$key] = mb_convert_encoding($value, $fontType, 'utf-8');

        }
        if ($isFirst) {
            fputcsv($fp, $headers);
        }
        //计数器
        $num   = 0;
        $limit = 50000;
        //逐行取出数据，不浪费内存
        $count = count($data);
        for ($i = 0; $i < $count; $i++) {
            $num++;
            if ($limit % 200 == $num) {
                ob_flush();
                flush();
                $num = 0;
            }
            $row = $data[$i];
            $ret = [];
            foreach ($headers as $key => $value) {
                if (!empty($specHeaders) && in_array($key, $specHeaders)) {
                    $ret[$key] = mb_convert_encoding($row[$key], $fontType, 'utf-8') . "t";
                } else {
                    $ret[$key] = mb_convert_encoding($row[$key], $fontType, 'utf-8');
                }
            }
            fputcsv($fp, $ret);
        }
        unset($data);
        unset($ret);
        fclose($fp);
        exit;
    }