php导出数据到csv文件

$count = M('revieworder')->where($map)->count();
set_time_limit(0);
ini_set('memory_limit', '256M');
$filename = '预约' . time() . '.csv';
header("Content-type:text/csv");
header('Content-Disposition: attachment;filename="' . $filename . '"');
header('Cache-Control: max-age=0');
// 打开PHP文件句柄，php://output 表示直接输出到浏览器
$fp = fopen('php://output', 'a');
$head = array('编号','姓名','手机号','预约日期','***','区域','短信发送','备注','申请时间');
foreach ($head as $i => $v) {
    // CSV的Excel支持GBK编码，一定要转换，否则乱码
    $head[$i] = iconv('utf-8', 'gbk', $v);
}
// 将数据通过fputcsv写到文件句柄
fputcsv($fp, $head);
// 从数据库中获取数据，为了节省内存，不要把数据一次性读到内存，从句柄中一行一行读即可
$limit = 10000;
for ($i = 0; $i < $count; $i = $i + $limit) {
    $list = M('revieworder')->where($map)->order('createtime desc')->limit($i, $limit)->select();
    foreach ($list as $k => $val) {
        $rows[0] = iconv('utf-8', 'gbk', $k + 1);
        $rows[1] = iconv('utf-8', 'gbk', "\t" . $val['realname']);
        $rows[2] = iconv('utf-8', 'gbk', $val['mobile']);
        $rows[3] = iconv('utf-8', 'gbk', "\t" . getSubstr($val['orderdate'],0,10).' '.$val['amorpm']);
        $rows[4] = iconv('utf-8', 'gbk', $val['subject']);
        $rows[5] = iconv('utf-8', 'gbk', $val['area']);
        $rows[6] = iconv('utf-8', 'gbk', $val['issend'] == '1'?'已发送':'未发送');
        $rows[7] = iconv('utf-8', 'gbk', $val['note']);
        $rows[8] = iconv('utf-8', 'gbk', time_format($val['createtime']));
        fputcsv($fp, $rows);
        unset($rows);
    }
    ob_flush();
    flush();  //刷新buffer
}
exit;