สอบถามวิธีใช้ jquery ในการล็อคอิน โดยไม่เปลี่ยนหน้าครับ ถ้าใส่รหัสถูก ให้โชว์อีกแบบ ถ้าใส่ผิดให้กรอกใหม่ แต่มีข้อความเตือนว่าผิดครับ

<script>
$(document).ready(function(){
    $("#add_err").css('display', 'none', 'important');
     $("#login").click(function(){    
          username=$("#name").val();
          password=$("#word").val();
          $.ajax({
           type: "POST",
           url: "login.php",
            data: "name="+username+"&pwd="+password,
           success: function(html){    
            if(html=='true')    {
             //$("#add_err").html("right username or password");
             window.location="dashboard.php";
            }
            else    {
            $("#add_err").css('display', 'inline', 'important');
             $("#add_err").html("<img src='images/alert.png' />Wrong username or password");
            }
           },
           beforeSend:function()
           {
            $("#add_err").css('display', 'inline', 'important');
            $("#add_err").html("<img src='images/ajax-loader.gif' /> Loading...")
           }
          });
        return false;
    });
});

</script>

<div class="loginform-in">
<h1>User Login</h1>
<div class="err" id="add_err"></div>
<fieldset>
    <form action="./" method="post">
        <ul>
            <li> <label for="name">Username </label>
            <input type="text" size="30"  name="name" id="name"  /></li>
            <li> <label for="name">Password</label>
            <input type="password" size="30"  name="word" id="word"  /></li>
            <li> <label></label>
            <input type="submit" id="login" name="login" value="Login" class="loginbutton" ></li>
        </ul>
         </form>    
</fieldset>
</div>

session_start();
$uName = $_POST['name'];
$pWord = md5($_POST['pwd']);
$qry = "SELECT usrid, username, oauth FROM usermeta WHERE username='".$uName."' AND pass='".$pWord."' AND status='active'";
$res = mysql_query($qry);
$num_row = mysql_num_rows($res);
$row=mysql_fetch_assoc($res);
if( $num_row == 1 ) {
    echo 'true';
    $_SESSION['uName'] = $row['username'];
    $_SESSION['oId'] = $row['orgid'];
    $_SESSION['auth'] = $row['oauth'];
    }
else {
    echo 'false';
}