PHP下载文件

$filename = $_GET['file']; //Get the fileid from the URL 
// Query the file ID 
$query = sprintf("SELECT * FROM tableName WHERE id = '%s'",mysql_real_escape_string($filename)); 
$sql = mysql_query($query); 
if(mysql_num_rows($sql) > 0){ 
    $row = mysql_fetch_array($sql); 
    // Set some headers 
    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=".basename($row['FileName']).";"); 
    header("Content-Transfer-Encoding: binary"); 
    header("Content-Length: ".filesize($row['FileName'])); 

    @readfile($row['FileName']); 
    exit(0); 
}else{ 
    header("Location: /"); 
    exit; 
}