php csv 导出

$str = "帐号,FBA(SKU),公司(SKU),期初库存,备货入库,退货入库,转仓入库,盘盈入库,其它入库,入库合计,销售出库,转仓出库,盘亏出库,其它出库,出库合计,实际期末库存,理论期末库存,实际比理论相差\n";
foreach($data as $k =>$v) {
$str .= $v['account_name'].",".$v['sku'].",".$v['piv_sku'].",".$v['qckc'].",".$v['bhrk'].",".$v['thrk'].",,".$v['pyrk'].",,".
$v['rkhj'].",".$v['xsck'].",,".$v['pkck'].",".$v['qtck'].",".$v['ckhj'].",".$v['qmkc'].",".$v['llqmkc'].",".$v['diff']."\n";
}
$fileName = date('YmdHis').".csv";
header("Content-type:text/csv");
header("Content-Disposition:attachment;filename=".$fileName);
header('Cache-Control:must-revalidate,post-check=0,pre-check=0');
header('Expires:0');
header('Pragma:public');
echo $str;
die;