title: long-polling info from mysql not working
body: <p>I'm trying to make long-polling based chat with ajax, jquery, php and mysql, but something seems wrong (also i'm new to long-polling).</p>
  
  <p>index.php:</p>
  
  <pre><code> &lt;?php
  include 'db.php';
  $result = mysql_query("SELECT id FROM chatpoll ORDER BY id DESC LIMIT 1");
  while($row = mysql_fetch_array($result))
  {
      $old_msg_id = $row['id'];
  }
  ?&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;script src="http://jqueryjs.googlecode.com/files/jquery-1.3.2.min.js" type="text/javascript" charset="utf-8"&gt;&lt;/script&gt;
      &lt;script type="text/javascript" charset="utf-8"&gt;
  
          var old_msg_id = &lt;?php echo $old_msg_id; ?&gt;;
  
          function waitForMsg(){
              $.ajax({
                  type: "GET",
                  url: "poll.php?old_msg_id=" + old_msg_id,
                  async: true,
                  cache: false,
  
                  success: function(data){
                      var json = eval('(' + data + ')');
                      if(json['msg'] != "") {
                          alert("New msg added to base!");
                      }
                      old_msg_id = json['old_msg_id'];
                      setTimeout('waitForMsg()',1000);
                  },
                  error: function(XMLHttpRequest, textStatus, errorThrown){
                      alert("error: " + textStatus + " (" + errorThrown + ")");
                      setTimeout('waitForMsg()',15000);
                  }
              });
          }
          $(document).ready(function(){
              waitForMsg();
          });
          function load(old_msg_id) //part of code which i'm not using yet
          {
              $.get('getmsg.php?last_msg_id='+ old_msg_id, function(data){
                  $('#chat').append(data);
              }, 'html');
          }
      &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div id="chat"&gt;
      &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>and poll.php</p>
  
  <pre><code> &lt;?php
  include 'db.php';
  $old_msg_id = $_GET['old_msg_id'];
  $result = mysql_query("SELECT id FROM chatpoll ORDER BY id DESC LIMIT 1");
  while($row = mysql_fetch_array($result))
  {
      $last_msg_id = $row['id'];
  }
  while($old_msg_id &gt;= $last_msg_id) {
      usleep(1000);
      clearstatcache();
      $old_msg_id = $last_msg_id;
  }
  $response = array();
  $response['msg'] = 'new';
  $response['old_msg_id'] = $old_msg_id;
  echo json_encode($response);
  ?&gt;
  </code></pre>
  
  <p>it's not showing any error both in index.php and poll.php, but when i insert data with bigger id than old_msg_id nothing happens..</p>