单击时替换选项卡中的代码

我需要一点帮助与我的网站涉及私人消息的部分之一。有问题的页面上有4个选项卡，其中一个选项卡称为收件箱显示了收到的所有消息的表，每个消息的主题都有一个链接，可以转到另一个页面，更详细地显示该消息。然而，我想要的是收件箱选项卡中的内容被用于更详细地显示消息的代码所取代。

<div id="inbox" class="tab_content">
    <table id="mail_header">
              <tr class="mailHeader">
                <th>Message ID</th>
                <th>From</th>
                <th>Subject</th>
                <th>Content</th>
                <!--<th>Date Completed</th>-->
                <th>Date Sent</th>
                <!--<th>Refused</th>-->
                </tr>
                        <?php
                        $sql = mysql_query("SELECT * FROM user_message WHERE id=$id");
                        $rowCheck = mysql_num_rows($sql);
                        if ($rowCheck == 0) {
                           echo "You Have No Messages";
                           die;
                        }
                        else {
                           while ($query = mysql_fetch_array($sql)) {
                                    echo '<div id="message_content">';
                                  echo '<tr>';
                                  $message_id = $query['message'];
                                  $from = $query['from'];
                                  $subject = $query['subject'];
                                  $message_content = $query['message_content'];
                                  $date_sent = $query['date_sent'];
                                  $viewed = $query['viewed'];
                                  if($viewed == '0'){
                                    echo "<td><boldMail>$message_id</boldMail></td>";
                                    echo "<td><boldMail>$from</boldMail></td>";
                                    echo "<td><boldMailSubject><a href='mail.php?mail=$message_id'>$subject</a></boldMail></td>";
                                    echo "<td><boldMail><div>$message_content</div></boldMail></td>";
                                    echo "<td><boldMail>$date_sent</boldMail></td>";
                                  }
                                  else{
                                    echo "<td>$message_id</td>";  
                                    echo "<td>$from</td>";
                                    echo "<td><a href='mail.php?mail=$message_id'>$subject</a></td>";
                                    echo "<td><div>$message_content</div></td>";
                                    echo "<td>$date_sent</td>";
                                  }

                                  echo '</tr>';
                                  echo '</div>';
                           }
                        }
                        ?>
                </table>
</div>

下面是我想在点击其中一个消息时替换上面代码的代码

<?php
        $mail_id = "";
        $mail_id = $_GET['mail'];
        if($mail_id = ""){
            $string = get_include_contents('mailContent.php');
            echo "$string";
        }
        else{
            $mail_id = "";
            $mail_id = $_GET['mail'];
            $sql_mail = mysql_query("SELECT * FROM user_message WHERE message='$mail_id'");
            $mail_array = mysql_fetch_assoc($sql_mail);
            $message_id = $mail_array['message'];
            $from = $mail_array['from'];
            $subject = $mail_array['subject'];
            $message_content = $mail_array['message_content'];
            $date_sent = $mail_array['date_sent'];
            echo "$message_id";
            echo "$from";
            echo "$subject";
            echo "$message_content";
            echo "$date_sent";
        }
        ?>

谢谢你的想法，即使你可以告诉我如果我需要actionscript或javascript等…