PHP将mysql数据导出到excel表，但在浏览器中显示

我正在尝试将数据从PHP mysql导入excel，并且它运行良好。但一旦我点击导入按钮，它就会在浏览器中显示。

header("Content-Disposition: attachment; filename=faculty-export.xls");
header("Content-type: application/vnd-ms-excel; charset=UTF-8;");

我已经在我的PC（Windows 7，IIS，PHP 5.4）中测试了本地数据，它运行良好，但当我在web服务器（PHP 5.3，Linux，Apache 2.2.3）上上传时，导出数据显示在浏览器中（测试浏览器IE 10，11，Firefox和Chrome）。

我面临的问题是因为我们必须更改服务器中的一些设置，或者我必须对编码中的某些内容做些什么？

发布数据

 <form method="post" action="export_excel.php">
<input type="hidden" name="excel_name" value="<?php echo $_GET['name']; ?>">
<input type="hidden" name="excel_gender" value="<?php echo $_GET['gender']; ?>">
<input type="hidden" name="excel_college" value="<?php echo $ColName; ?>">
<input type="hidden" name="excel_department" value="<?php echo $_GET['deptf']; ?>">
<input type="hidden" name="excel_nationality" value="<?php echo $_GET['natf']; ?>">
<input type="hidden" name="excel_finalstatus" value="<?php echo $_GET['fstatusf']; ?>">
<input type="hidden" name="excel_fyear" value="<?php echo $_GET['fyearf']; ?>">
  <input style="float:left;" type="submit" value="Save to Excel">
</form>

下面是export_excel.php.的代码

<?php
  error_reporting(0);
  include("connectdb.php"); 
  if (empty($_POST['excel_name']) && empty($_POST['excel_gender']) && empty($_POST['excel_college']) && empty($_POST['excel_department']) && empty($_POST['excel_nationality']) && empty($_POST['excel_finalstatus']) && empty($_POST['excel_fyear']))
{
    /*$query="select * from ab";*/
    $query="select * from ab";
}
 else
    {
         $wheres = array();
          $query = "select * from ab where ";
   if (isset($_POST['excel_name']) and !empty($_POST['excel_name']))
{
    $wheres[] = "name like '%{$_POST['excel_name']}%' ";
} 
if (isset($_POST['excel_gender']) and !empty($_POST['excel_gender']))
{
    $wheres[] = "gender = '{$_POST['excel_gender']}'";
} 
if (isset($_POST['excel_college']) and !empty($_POST['excel_college']))
{
    $wheres[] = "college = '{$_POST['excel_college']}' ";
} 
if (isset($_POST['excel_department']) and !empty($_POST['excel_department']))
{
    $wheres[] = "department = '{$_POST['excel_department']}' ";
} 
if (isset($_POST['excel_nationality']) and !empty($_POST['excel_nationality']))
{
    $wheres[] = "nationality = '{$_POST['excel_nationality']}' ";
} 
if (isset($_POST['excel_finalstatus']) and !empty($_POST['excel_finalstatus']))
{
    $wheres[] = "finalstatus = '{$_POST['excel_finalstatus']}' ";
}
if (isset($_POST['excel_fyear']) and !empty($_POST['excel_fyear']))
{
    $wheres[] = "fyear = '{$_POST['excel_fyear']}' ";
} 
foreach ( $wheres as $where ) 
{
  $query .= $where . ' AND ';   //  you may want to make this an OR
 }
   $query=rtrim($query, "AND "); 
  }
   $result = mysqli_query($conn,$query);
    $xls_filename = 'export_'.date('d-m-Y').'.xls'; // Define Excel (.xls) file name

 header("Pragma: public");
 header("Expires: 0");
 header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
 header("Content-Type: application/force-download");
 header("Content-Type: application/octet-stream");
 header("Content-Type: application/download");;
 header("Content-Disposition: attachment; filename=$xls_filename");
 header("Content-Transfer-Encoding: binary "); 

echo "<table border='1'><tr><th>الإسم</th><th>تاريخ وصول الملف</th><th>الكلية</th><th>القسم</th><th>العمر</th><th>الجنسية</th><th>الجنس</th><th>الدرجة</th><th>نوع التعيين</th><th>السنة</th><th>البكالوريوس<br>سنة التخرج</th><th>الماجستير<br>سنة التخرج</th><th>الدكتوراه<br>سنة التخرج</th><th>الملاحظات</th><th>تاريخ اللجنة</th>";


while($res = mysqli_fetch_assoc($result)){ 
echo "<tr><td>".$res['name']."</td><td>".$res['DOA']."</td><td>".$res['college']."</td><td>".$res['department']."</td><td>".$res['DOB']."</td><td>".$res['nationality']."</td><td>".$res['gender']."</td><td>".$res['fwtype']."</td><td>".$res['finalstatus']."</td><td>".$res['fyear']."</td>";
$query2 = "SELECT * FROM abc where ".$res['id']." = DId";
$result1 = mysqli_query($conn,$query2);
if (mysqli_num_rows($result1) > 0) {
    while($row = mysqli_fetch_assoc($result1)) {
    echo "<td>".$row['DUName']."<br>".$row['DYEAR']."</td>";    
    }
    }
    }
  echo "</tr></tr></table>";

    exit();
 ?>