从数据库 php 下载文件错误

我已经阅读了我能找到的关于这个主题的所有教程，但没有一个帮助解决了我的问题。我不知道为什么，但是每当我单击下载按钮时，我的代码都会给我一个html文件，而不是下载图像文件。

.HTML：

<a href="getfile.php?id=1">Download Now</a>

.PHP：

<?php
$id= $_GET['id'];
$con= mysqli_connect("localhost","root","","dbname");
    if (mysqli_connect_errno($con))
     {
        echo "<script type='"text/javascript'">alert('Failed To connect to  MySQL: "+"mysqli_connect_error();"+"');</script>";
    }
    else
    {
        $sql = "SELECT * FROM users_files WHERE file_id = ".$id;
        $result = mysql_query($sql);
         $row_cnt = mysqli_num_rows($result);
         echo "<script type='"text/javascript'">alert('".$row_cnt."');</script>";
        if(!$result || !mysql_num_rows($result)){
            echo "<script type='"text/javascript'">alert('Invalid file chosen.');</script>";
            //echo '<script language="javascript" type="text/javascript" >';
        //echo ' window.location.assign("ViewMyFiles.php");';
        //echo '</script>';
        mysqli_close($con);
            }
            $curr_file = mysql_fetch_assoc($result);
            $size = $curr_file['file_size'];
            $type = $curr_file['file_type'];
            $name = $curr_file['file_name'];
            $content = $curr_file['file_content'];
            header("Content-length: ".$size."");
            header("Content-type: ".$type."");
            header('Content-Disposition: attachment; filename="'.$name.'"');
            readfile($content);
            $_SESSION['email']=$nemail;
            mysqli_close($con);
    }
?>

我将上面的PHP文件命名为getfile.php，下载结果为getfile.htm。