how Submit forms with POST method and connect mysql using AJAX?

hi all,
i want connect DB and get value from DB, then send the value to javascript function on the same page , it's looks like have to using ajax,
please someone else can tell me how to do ???

<script>
function excuteApplet()
        {
            document.getElementById('myapplet').go();
             return true;
        }
</script>
<?
     if($_POST["submit"]=="Test")
                {      
                         require_once("DB_config.php");
                          require_once("DB_class.php");
                         $db = new DB;
                        $db->connect_db($_DB['host'], $_DB['username'], $_DB['password'], $_DB['dbname']);
                        $db->query("select ID,valueA, valueB from customer ;");
                      while($row = $db->fetch_array())
                         {
                                $valueA= $row['valueA'];
                                $valueB= $row['valueB'];
                                $ID= $row['ID'];
                                 $sql = "update customer set paid=1 where ID = '".$ID."'";
                                $result = $db->update($sql);
                                  $value= $valueA;
                                        if($total>30)
                                        {
                                                $value= trim($valueA);
                                        }
                                       else
                                         {
                                              $value= trim($valueB);
                                        }
                              }  //end while
               } //end if
        ?>
                   <applet id="myapplet" code="myapplet.class" name="myapplet" width="0" height="0" >
                              <PARAM NAME=customer VALUE=<? echo $value?>>   //get the value from dB , when form data have been send.....but how to do ????
                    </applet>

                    <form action=""  name="form1"  method="post">  
                     <input  name="btn" type="submit" value="Test" id="Test"   >
                    </form>

 

Code (markup):

 

you can use jquery instead of xml HTTP Request .It is easy and good.

First of all include jquery file to your page and

function form_post(url,div_id){
$('#'+div_id).html("<table width=100% height=100%><tr><td style='height:324px;width=300px;' valign='middle' align='center'><img src='loading_div.gif'/></td></tr></table>");
$.post(url, {
email: $('#email').val()
}, function(response){
setTimeout("LoadContent('"+div_id+"', '"+escape(response)+"')", 500);
});
return false;
}
function LoadContent(div_id, response) {
$('#'+div_id).html(unescape(response));
}

url="Path of the url where your data of form to be submitted"

div id = "responce load"

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