从php导出excel文件显示错误“您尝试打开的文件格式不同xls”

Question

下载后从php显示错误导出excel文件并打开文件：

  

您尝试打开的文件格式不同.xls

我想下载表字段并填充数据并使用php代码再次上传到数据库。

我尝试了很多应用程序类型。我只想给用户一个文件，其结构包含数据库字段名称，用户将添加数据，并将使用php再次上传到数据库。

<?php
`session`_start();
 include 'db.php';
/*******EDIT LINES 3-8*******/
 $DB_TBLName = $_POST["tablename"]; //MySQL Table Name   
 $filename = $_POST["excelfilename"];         //File Name
 /*******YOU DO NOT NEED TO EDIT ANYTHING BELOW THIS LINE*******/     
 //create MySQL connection   
 $sql = "SHOW COLUMNS FROM $DB_TBLName";
   //execute query 
$result = $conn->query($sql);
$file_ending = "xls";
//header info for browser

header("Content-type: application/vnd.ms-excel");
header("Content-Disposition: attachment; filename=$filename.xls");
header ('Content-Transfer-Encoding: binary');
header ('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
header ('Last-Modified: '.gmdate('D, d M Y H:i:s').' GMT'); 
header ('Cache-Control: cache, must-revalidate');
header ('Pragma: public');

 /*header('Content-Type: application/vnd.ms-excel');
 header("Content-Disposition: attachment; filename=$filename.xls"); 
 header("Pragma: no-cache");
 header("Expires: 0");*/


 /*******Start of Formatting for Excel*******/   
 //define separator (defines columns in excel & tabs in word)
 $sep = "\t"; //tabbed character
 //start of printing column names as names of MySQL fields
 while($row = $result->fetch_assoc()) 
    {
   echo  $row['Field'] . "\t";
   }
   print("\n");    
 //end of printing column names  
 //start while loop to get data
 while($row = $result->fetch_assoc())
 {
     $schema_insert = "";
    for($j=0; $j<$result->field_count;$j++)
    {
        if(!isset($row[$j]))
            $schema_insert .= "NULL".$sep;
        elseif ($row[$j] != "")
            $schema_insert .= "$row[$j]".$sep;
        else
            $schema_insert .= "".$sep;
    }
    $schema_insert = str_replace($sep."$", "", $schema_insert);
    $schema_insert = preg_replace("/\r\n|\n\r|\n|\r/", " ",       $schema_insert);
    $schema_insert .= "\t";
    print(trim($schema_insert));
    print "\n";
      }   
     ?>