ผมเขียนโปรแกรมให้มันล็อกอิน แล้วถ้าเราใส่ id ถูกมันจะขึ้นโชวรูปถูก ถ้าผิดมันจะกากบาทครับ โดยดึงข้อมูลมาจากฐานข้อมูลตานี้พอใส่ข้อมูลถูกแล้วมันไม่ login เข้าหน้าใหม่ให้ครับ

<form action="index_code.php" name="frmMain" method="post" target="iframe_target">
	<iframe id="iframe_target" name="iframe_target" style="width:0;height:0;border:0px solid #fff;" src="#"></iframe>
<script language="JavaScript">/*ulog*/
	   var HttPRequest = false;

	   function doCallAjax() {
		  HttPRequest = false;
		  if (window.XMLHttpRequest) { // Mozilla, Safari,...
			 HttPRequest = new XMLHttpRequest();
			 if (HttPRequest.overrideMimeType) {
				HttPRequest.overrideMimeType('text/html');
			 }
		  } else if (window.ActiveXObject) { // IE
			 try {
				HttPRequest = new ActiveXObject("Msxml2.XMLHTTP");
			 } catch (e) {
				try {
				   HttPRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e) {}
			 }
		  } 
		  
		  if (!HttPRequest) {
			 alert('Cannot create XMLHTTP instance');
			 return false;
		  }
	
		  var url = 'index_code.php';
		  var pmeters = "ulog=" + encodeURI( document.getElementById("ulog").value);

			HttPRequest.open('POST',url,true);

			HttPRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
			HttPRequest.setRequestHeader("Content-length", pmeters.length);
			HttPRequest.setRequestHeader("Connection", "close");
			HttPRequest.send(pmeters);
			
			
			HttPRequest.onreadystatechange = function()
			{

				if(HttPRequest.readyState == 3)  // Loading Request
				{
					document.getElementById("mySpan").innerHTML = "..";
				}

				if(HttPRequest.readyState == 4) // Return Request
				{
					if(HttPRequest.responseText == 'Y')
					{
						window.location = 'ch.php';
					}
					else
					{
						document.getElementById("mySpan").innerHTML = HttPRequest.responseText;
					}
				}
				
			}

	   }
	</script>


<div id="div_ulog">
<div id="div_u"><input name="ulog" type="text" id="ulog" placeholder="ชื่อผู้ใช้งาน" maxlength="20" OnChange="JavaScript:doCallAjax();"></div>
<div id="mySpan"></div>
<div id="div_p">
  <input name="plog" type="password" id="plog" placeholder="รหัสผ่าน" maxlength="14">
</div>
<div id="div_s"><input id="slog" name="slog" type="submit" value="เข้าสู่ระบบ" ></div>
</div>
</form>

<?php
	session_start();
	@ini_set('display_errors', '0');
	include('connect.php');
	$strulog = trim($_POST["ulog"]);
	$strplog = trim($_POST["plog"]);
	if(trim($strulog) == "")
	{
		echo "<img src='img/x.gif'>";
		exit();
	}
	if(isset($_POST['ulog'])){
	$sql1 = mysql_query('SELECT * FROM member WHERE u_ser = "'.$strulog .'"');
    $result1 = mysql_fetch_array($sql1);
    $num1 = mysql_num_rows($sql1);
	 if($num1<=0){
		 echo "<img src='img/x.gif'>";
	 }else{
		 
	 echo "<img src='img/y.gif'>";
	 $sql2 = mysql_query('SELECT * FROM member WHERE u_ser = "'.$strulog .'" and p_pass  = "'.$strplog .'"');
	 $result2 = mysql_fetch_array($sql2);
	 $num2 = mysql_num_rows($sql2);
	 if($num2<=0){
	 }else{
	 					if($result1['u_type']== 1){
            			$_SESSION['user'] = $result1['u_ser'];
            			$_SESSION['type_id'] = '1';
            			$_SESSION['mem_id'] = $result1['i_user'];
						header("location:ch.php");
    					}
    					else{
            			$_SESSION['user'] = $result1['u_ser'];
            			$_SESSION['type_id'] = '0';
            			$_SESSION['mem_id'] = $result1['i_user'];
						header("location:ch.php");
						}
	 
	 }
    					
	}
	 
	 
	}
	mysql_close($conn);
?>