使用表单中的按钮更新数据

我想更新alumni_request表中的数据。首先，它将显示数据，下面是一个"批准"按钮。单击该按钮时，alu_request_status列将从 0 更新为 1。下面是我的表单代码：

                                                    <?php                                       
            $data = "Select * from alumni_request";         
                $result = mysql_query($data) or die(mysql_error());                         
                    while($info = mysql_fetch_array( $result )) 
                    {
                    $alu_request_id = $info['alu_request_id']  ;
                    $alu_request_description = $info['alu_request_description']  ;
                    $alu_request_date = $info['alu_request_date']  ;
                    $student_std_matric = $info['student_std_matric']  ;

                    ?>
                                                    <div class="space-4"></div>
                                                            <p><label>Description:</label>  <?php echo $alu_request_description; ?></p>
                                                            <p><label>Date:</label>  <?php echo $alu_request_date; ?></p>
                                                            <p><label>By:</label>  <?php echo $student_std_matric; ?></p>
                                                            <p>
                                                                <form action="admin-respond-alu-req-processor.php" method="post">
                                                                    <button type="submit" class="btn btn-primary" name="alu_request_status" value="approve">Approve</button>
                                                                </form></p>
                                                                <hr>

                    <?php
                    }
                    ?>  

下面是 admin-respond-alu-req-processor 的代码.php

<?php
    if(isset($_POST['approve']))
{
    $dbhost = 'localhost';
    $dbuser = 'root';
    $dbpass = '';
    $conn = mysql_connect($dbhost, $dbuser, $dbpass);
    if(! $conn )
    {
    die('Could not connect: ' . mysql_error());
    }
$alu_request_id = $_POST['alu_request_id'];
$sql = "UPDATE alumni_request SET alu_request_status = 1 WHERE alu_request_id = $alu_request_id";
    mysql_select_db('fskmkeda');
    $retval = mysql_query( $sql, $conn );
    if(! $retval )
    {
    die('Could not update data: ' . mysql_error());
    }
    echo "Updated data successfully'n";
    mysql_close($conn);
}
else
{
header('Location: '."admin-respond-alu-req.php");
?>
<?php
}
?>

代码不起作用。我关注了这个网站，做了一些小改动：http://www.tutorialspoint.com/php/mysql_update_php.htm

请帮助我：'（