php输出数据到csv文件

 function export()
{
	$fileName = date('Y-m-d').uniqid().'.csv';
	set_time_limit(0);
	ini_set('memory_limit', '1024M');
	// 设置header信息
	header('Content-Type: application/octet-stream');
	header('Content-Disposition: attachment; filename=' . $fileName);

	// 设置标题
	$title = ["列名1", "列名1","列名1", "列名1"];

	echo iconv('utf-8', 'gbk//TRANSLIT', '"' . implode('","', $title) . '"' . "\n");

	$sql = "select xxx";
	$result = $this->db_w->fetch($sql);

	foreach($result as $k=>$v){
		if($k/500 == 0){
			ob_flush();
			flush();
		}

		$str_arr = array();

		$str_arr[] = $v['aaa'];
		$str_arr[] = $v['bbb'];

		$str_arr[] = $v['ccc']
		$str_arr[] = $v['ddd'] 

		echo iconv('utf-8', 'gbk//TRANSLIT', '"' . implode('","', $str_arr) . '"' . "\n");

	}
	exit;

}