如何在PHP类中使用ajax

this is my botton:

            <form>
<input type="hidden"  id="id" value="'.$row['order_id'].'">         
<input type="button" value="Delete" onclick="ajaxFunction()">
            </form>

this is the ajax function:

<script language="javascript" type="text/javascript">
<!-- 
//Browser Support Code
function ajaxFunction(){
    var ajaxRequest;  // The variable that makes Ajax possible!

    try{
        // Opera 8.0+, Firefox, Safari
        ajaxRequest = new XMLHttpRequest();
    } catch (e){
        // Internet Explorer Browsers
        try{
            ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try{
                ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e){
                // Something went wrong
                alert("Your browser broke!");
                return false;
            }
        }
    }
    // Create a function that will receive data sent from the server
    ajaxRequest.onreadystatechange = function(){
        if(ajaxRequest.readyState == 4){
            document.myForm.time.value = ajaxRequest.responseText;
        }
    }
    var id = document.getElementById(\'id\').value;
    var queryString = "?id=" + id;
    ajaxRequest.open("GET", "classes/ajaxed/reservation_functions.php" + queryString, true);
    ajaxRequest.send(null); 
}

//-->
</script>

and here is the php file that handles this function called reservation_functions.php:

<?php
$id = $_GET['id'];
require_once '../class.db.php';
require_once '../../includes/constants.php';
$db = new MySQL(DB_SERVER, DB_USER, DB_PASSWORD, DB_NAME, false);

$db->query("DELETE FROM orders WHERE order_id = $id;") or die(mysql_error());
echo 'DONE!';

?>

I am really good with PHP but I am really far from AJAX so my question is how to handle different parameters with ajax, to be more clear: I want to add a delete function, Print function, Edit function but I want to make one php file to handle all the functions and those function to come with AJAX.

It is a little bit hard for me to come up with idea because I am really far from AJAX,

Thank you for your time and help.

How about:

switch (strtolower($_GET['action'])) {
    case 'delete' :
        // delete …
        break;
    case 'add' :
        // add …
        break;
    case 'foobar' :
        // foobar …
        break;
    default :
        // 404
}

Then call the URL with the additional action parameter: ?action=delete&....

you can do it:

Class:

class AjaxActions {

   private static $instance;

   private function __construct () {}

   public static class getInstance() {

        if (!self::$instance) self:$instance = new self();

        return self::$instance;
   }

   private function makeReturn ($action, $data) {
        return json_encode(array(
             'action' => (string) $action,
             'time' => time(),
             'result' => $data
        ));
   }

   public function delete ($request) {
        $db = new MySQL(DB_SERVER, DB_USER, DB_PASSWORD, DB_NAME, false);
        $id = (int) $request['id'];

        $db->query("DELETE FROM orders WHERE order_id = $id;");

        if (!$db->errn) {
            $error = 0;
            $emsg = "";
        } else {
            $error = $db->errn;
            $emsg = $db->error;
        }

        return $this->makeReturn('delete', array(
            'error' => $error,
            'errorMessage' => $emsg
        ));

   }

   // Other actions here..

}

And...

$action = isset($_REQUEST['action']) ? $_REQUEST['action'] : null;

if ($action) {

   $oAjaxCommand = AjaxActions::getInstace();

   if (method_exists($oAjaxCommand,$action) {
        $response = call_user_func (array($oAjaxCommand,$action),$_REQUEST);
        echo $response;
        exit(0);
   } else {
        thrown new Exception("Action not exists");
   }

}

From de javascript side, you resive a json object with the response. I recomended use a JS framework like mootools or jquery. This frameworks do the ajax work much easy, and cross-browser.