AJAX，PHP＆amp; MySQL聊天室：检索邮件时找不到页面

Question

我目前正在PHP项目中构建一个非常简单的AJAX聊天室，设计师可以与客户进行交互。

问题在于，保存消息功能确实有效，但当我尝试显示所有已保存的消息时，它只显示在聊天部分：Page not found。我的猜测是问题在XMLHttpRequest范围内，但我似乎找不到更多我想要的解决方案。

我的主要PHP文件（聊天所在的位置）：

<aside class="contentcomment">
        <h1>Comments</h1>
        <div class="input-form"> 
            <!--div to recieve the certain errors-->
            <div id="error">

            </div>

            <!--div to send the message-->
            <div id="write"> 
                <input type="text" id="text" maxlength="255" placeholder="Comment..."/>
                <input type="hidden" id="name" value="<?php echo ($myusername);?>">
                <input type="hidden" id="client" value="<?php echo ($client);?>">
                <input type="hidden" id="designid" value="<?php echo ($designid);?>">
                <input type="button" id="commentbutton" value="Send" onclick="send();"/>
            </div>

            <!--div to recieve the messages-->                  
                <ul class="chats">
                    <div id="messages"></div>
                </ul>  
        </div> <!--end demo-wrapper-->

        <script type="text/javascript">
            //This function will display the messages
            function showmessages(){

                //Send an XMLHttpRequest to the 'show-message.php' file
                if(window.XMLHttpRequest){
                    xmlhttp = new XMLHttpRequest();
                    xmlhttp.open("GET","show-messages.php",false);
                    xmlhttp.send(null);
                }

                else{
                    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
                    xmlhttp.open("GET","show-messages.php",false);
                    xmlhttp.send();
                }

                //Replace the content of the messages with the response from the 'show-messages.php' file
                document.getElementById('messages').innerHTML = xmlhttp.responseText;

                //Repeat the function each 30 seconds
                setTimeout('showmessages()',30000);
            }

            //Start the showmessages() function
            showmessages();

            //This function will submit the message
            function send(){
                //Send an XMLHttpRequest to the 'send.php' file with all the required informations
                var sendto = 'send.php?message=' + document.getElementById('text').value + 
                '&name=' + document.getElementById('name').value + '&client=' + document.getElementById('client').value + '&designid=' + document.getElementById('designid').value;

                if(window.XMLHttpRequest){
                    xmlhttp = new XMLHttpRequest();
                    xmlhttp.open("GET",sendto,false);
                    xmlhttp.send(null);
                }

                else{
                    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
                    xmlhttp.open("GET",sendto,false);
                    xmlhttp.send();
                }

                var error = '';

                //If an error occurs the 'send.php' file send`s the number of the error and based on that number a message is displayed
                switch(parseInt(xmlhttp.responseText)){
                    case 1:
                        error = 'The database is down!';
                        break;
                    case 2:
                        error = 'The database is down!';
                        break;
                    case 3:
                        error = 'Don`t forget the message!';
                        break;
                    case 4:
                        error = 'The message is too long!';
                        break;
                    case 5:
                        error = 'Don`t forget the name!';
                        break;
                    case 6:
                        error = 'The name is too long!';
                        break;
                    case 7:
                        error = 'This name is already used by somebody else!';
                        break;
                    case 8:
                        error = 'The database is down!';
                }

                if(error == ''){
                    document.getElementById('error').innerHTML = '';
                    showmessages();
                }

                else{
                    document.getElementById('error').innerHTML = error;
                }
            }
        </script>

    </aside>

然后这是我的“show-message.php”：

    <?php
    // All the connection info goes here...

    // Connect to server and select databse.
    $connect = mysql_connect("$host", "$username", "$password")or die(1); 
    mysql_select_db("$db_name")or die(2);

    //Get the first 10 messages ordered by time
    $result = mysql_query("SELECT * FROM Comment_Uploads ORDER BY Time DESC LIMIT 0,10");
    $messages = array();

    //Loop and get in an array all the rows until there are not more to get
    while($row = mysql_fetch_array($result)){
        //Put the messages in divs and then in an array
        $messages[] = "<li id=\"client\">" . $row[Comment] . "</li>";
        //The last posts date
        $old = $row[time];
    }

    //Display the messages in an ascending order, so the newest message will be at the bottom
    for($i=9;$i>=0;$i--){
        echo $messages[$i];
    }

    //This is the more important line, this deletes each message older then the 10th message ordered by time, so the table will never have to store more than 10 messages.
    //mysql_query("delete from chat where time < " . $old);
?>