Live edit of Information using Ajax and Jquery

<?php
include "database_connection.php";
if(isset($_POST['id']) && isset($_POST['firstname']) && isset($_POST['lastname']) && isset($_POST['email']) && !empty($_POST['id']) && !empty($_POST['firstname']) && !empty($_POST['lastname']) && !empty($_POST['email']))
{
      mysql_query("update `user_details` set `firstname` = '".mysql_escape_string(strip_tags($_POST['firstname']))."', `lastname` = '".mysql_escape_string(strip_tags($_POST['lastname']))."', `email` = '".mysql_escape_string(strip_tags($_POST['email']))."' where `id` = '".mysql_escape_string(strip_tags($_POST['id']))."'");
}
?>

<script type="text/javascript" src="1.5.2.main.js"></script>
<script type="text/javascript">
function vasplus_live_edit_area(details_id)
{
      $(".vasplus_live_edit_area").css("background-color","#FFF");
      $("#detail_a"+details_id).hide();
      $("#detail_b"+details_id).hide();
      $("#detail_c"+details_id).hide();
      $("#detail_aa"+details_id).show();
      $("#detail_bb"+details_id).show();
      $("#detail_cc"+details_id).show();
      $("#id"+details_id).css("background-color","#F6F6F6");
}
$(document).bind('mouseup', function()
{
      $(".vasplus_hidden_boxes").hide();
      $(".vasplus_live_content").show();
      $(".vasplus_live_edit_area").css("background-color","#FFF");
});
$(document).ready(function()
{
      $(".vasplus_live_edit_area").bind('change', function()
      {
            var details_id = $(this).attr('id').replace('id','');
            var detail_aa = $("#detail_aa"+details_id).val();
            var detail_bb = $("#detail_bb"+details_id).val();
            var detail_cc = $("#detail_cc"+details_id).val();
            var dataString = 'id=' + details_id + '&firstname=' + detail_aa + '&lastname='+detail_bb + '&email='+detail_cc;
            $("#detail_a"+details_id).html('<img src="load.gif" />');
            if(detail_aa != "" && detail_bb != "" && detail_cc != "")
            {
                  $.ajax({
                        type: "POST",
                        url: "save_changes.php",
                        data: dataString,
                        cache: false,
                        success: function()
                        {
                              $("#detail_a"+details_id).html(detail_aa);
                              $("#detail_b"+details_id).html(detail_bb);
                              $("#detail_c"+details_id).html(detail_cc);
                        }
                  });
            }
            else
            {
                  alert('That field can not be completely empty. Please enter some content. Thanks...');
                  return false;
            }
      });
});
</script>

<div id="id<?php echo $user_id; ?>" style="padding:8px; float:left; cursor:pointer;" class="vasplus_live_edit_area" onClick="vasplus_live_edit_area(<?php echo $user_id; ?>);" align="left">

<div style="width:236px;float:left;">
<span id="detail_a<?php echo $user_id; ?>" class="vasplus_live_content"><?php echo $firstname; ?></span>
<input type="text" value="<?php echo $firstname; ?>" class="vasplus_hidden_boxes" id="detail_aa<?php echo $user_id; ?>" style="display:none;width:180px;" />
</div>

<div style="width:236px;float:left;">
<span id="detail_b<?php echo $user_id; ?>" class="vasplus_live_content"><?php echo $lastname; ?></span>
<input type="text" value="<?php echo $lastname; ?>" class="vasplus_hidden_boxes" id="detail_bb<?php echo $user_id; ?>" style="display:none;width:180px;"/>
</div>

<div style="width:240px;float:left;">
<span id="detail_c<?php echo $user_id; ?>" class="vasplus_live_content"><?php echo $email; ?></span>
<input type="text" value="<?php echo $email; ?>" class="vasplus_hidden_boxes" id="detail_cc<?php echo $user_id; ?>" style="display:none;width:250px;"/>
</div>

</div>