使用PHPExcel将SQL数据从数据库导出到Excel

我正尝试使用PHPExcel将数据从我的数据库导出到Excel。 我用这个问题的代码。 编辑mysql到mysqli并将扩展名更改为xlsx格式。 但是,当我想打开文件,我得到以下错误(我翻译成英文,所以对不起我英文不好,如果不对)

无法打开文件交stream29-05-2017.xlsx,因为文件格式或文件扩展名无效。 检查文件是否没有损坏,文件扩展名是否与文件格式匹配。

这是我复制和更改的代码:

<?php require 'database.php'; require '../Classes/PHPExcel.php'; if (isset($_POST['exporteer'])) { $a = $_POST['organisatie_naam']; $b = $_POST['begin_datum']; $c = $_POST['eind_datum']; $datum = date("dmY"); $objPHPExcel = new PHPExcel(); $query = "SELECT * FROM register WHERE organisatie_naam = '$a' AND (registratie_aansluit_datum BETWEEN '$b' AND '$c'"; $result = mysqli_query($db, $query); $objPHPExcel = new PHPExcel(); $rowCount = 1; while ($row = mysqli_fetch_array($result)) { $objPHPExcel->getActiveSheet()->setCellValue('A'.$rowCount, $row['registratie_id']); $objPHPExcel->getActiveSheet()->setCellValue('B'.$rowCount, $row['registratie_soort']); $objPHPExcel->getActiveSheet()->setCellValue('C'.$rowCount, $row['organisatie_naam']); $objPHPExcel->getActiveSheet()->setCellValue('D'.$rowCount, $row['apparaat_naam']); $objPHPExcel->getActiveSheet()->setCellValue('E'.$rowCount, $row['client_naam']); $objPHPExcel->getActiveSheet()->setCellValue('F'.$rowCount, $row['dienst_naam']); $objPHPExcel->getActiveSheet()->setCellValue('G'.$rowCount, $row['functie_naam']); $objPHPExcel->getActiveSheet()->setCellValue('H'.$rowCount, $row['kosten_soort']); $objPHPExcel->getActiveSheet()->setCellValue('I'.$rowCount, $row['status_naam']); $objPHPExcel->getActiveSheet()->setCellValue('J'.$rowCount, $row['registratie_aansluit_datum']); $objPHPExcel->getActiveSheet()->setCellValue('K'.$rowCount, $row['registratie_afsluit_datum']); $objPHPExcel->getActiveSheet()->setCellValue('L'.$rowCount, $row['registratie_omschr']); $rowCount++; pr($objPHPExcel); } header('Content-Type: application/vnd.openxmlformats- officedocument.spreadsheetml.sheet'); header('Content-Disposition: attachment;filename="rapportage ' . $datum . '.xlsx"'); header('Cache-Control: max-age=0'); $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007'); $objWriter->save('php://output'); header("Location: ../rapportage.php"); } ?> 

任何人知道我是否错过了一些东西? 提前致谢!