如何计算下载数据库中FILE的次数？

I am having problems trying to get my system to count the number of times a files has been downloaded. The website has download buttons linking to the files which are stored on my database, and I would like to be able to count the amount of downloads per file to display as a statistic, ideally once they click the link to download, the column in the files table should be incremented,but i cant do that. i'm beginner in php. somebody can help me?this is my code to display the file.

              <h3 class="box-title">Senarai Borang Cuti</h3>
              <p>&nbsp;</p>
            </div><!-- /.box-header -->
            <div class="box-body">  
            <!-- Advanced Tables -->
                <div class="table-responsive">
                <?php
                    $raw_results = mysql_query("SELECT * FROM document WHERE doc_jenisfail= 'Cuti';"); 

                                        ?>

                    <table width="98%" class="table table-striped" id="dataTables-example">
                        <thead>
                                                        <table width="600" border="1">
      <tr>

      <th width="190" bgcolor="#756E37"class="sw" style="text-align: centre" scope="col">Tajuk Borang</th>
      <th width="30" bgcolor="#756E37" class="sw" style="text-align: centre" scope="col">Tarikh Upload</th>
      <th width="30" bgcolor="#756E37" class="sw" style="text-align: centre" scope="col">Memuat Turun</th>

    </tr>
                        </thead>
                        <tbody>
                        <?php 
                            while($results = mysql_fetch_array($raw_results)) {     ?>
                            <tr>
                                <td align="left"><?php echo $results['nama_file'];?></td>         

                                <td align="center"><?php echo $results['tanggal_upload'];?></td>

                                <td align="center"><a href="admin/<?php echo $results['file'] ?>" target= "_blank"><img src="images/download.png?key=<?php $results['nama_file'] ?>" /></a></td>

                            </tr>
                            <?php  } ?>
                            </tbody>
                        </table>
                          </p></td>

You can add +1 to downloads in your database and then redirect to file.

In your template use link like download.php?id=1, for downloading file with id 1.

Download.php Code:

<?php 
//name of file: download.php

$id = $_GET['id'];

//Check if the get number is really a number
if (ctype_digit($id)) {

//Add +1 to downloads
mysql_query("update `document` set `downloads`=`downloads`+1 where id='$id'") or die(mysql_error());

//Redirect to downloads
$download_file = mysql_fetch_array(mysql_query("select * from document where id='$id'")) or mysql_error();

header("Location: http://example.com/pdfs/$download_file[name].pdf");

} else {
  echo 'Wrong link';
}


?>