laravel excel循环导出

public function exportExcel(){         Excel::create('订单统计'.date('Y-m-d H_i_s'), function ($excel) {            $excel->sheet('order', function ($sheet) {                                    $data = Orders::where('type',2)->orderby('id','desc')->get(); //要用get()                    $sheet->appendRow(['老师姓名','联系方式','老师性别']);//这里是表头的名称                    foreach($data as $o){ //appendRow是导出一行，要导出数据表就要循环这个                        $sheet->appendRow([$o->teacher_name,(string)$o->teacher_mobile,$o->teacher_sex]);//进行循环                    }                            });        })->download('csv');            }