ถามเรื่อง login ค่ะ รบกวนด้วยนะค่ะ อยากถามเรื่อง login ค่ะ ถ้าเกิดว่าจะไม่ให้เป็น radio เลือก นักศึกษา กับอาจารย์

<?
session_start();
	include('condb.php');
	if (!empty($_POST['submit1'])){
		
			
	if($_POST['rdb'] == "1")
		{
	$strsql ="select * from tb_teach where teach_usr = '$_POST[userid]' and teach_pwd  = '$_POST[pwd]'";
		}
		else
		{
	$strsql ="select * from  tb_student  where std_id = '$_POST[userid]' and std_pwd  = '$_POST[pwd]'";
		}
	$res = mysql_query($strsql);
	if(mysql_num_rows($res) > 0)
		{
		$rs = mysql_fetch_array($res);

			if($_POST['rdb'] == "2")
				{
		$_SESSION['m_id'] = $rs['std_id'];
		$_SESSION['std_id'] = $rs['std_id'];
	                $_SESSION['std_name'] = $rs['std_name'];
		$_SESSION['std_sname'] = $rs['std_sname'];
		$_SESSION['level_name'] = $rs['level_name'];
                                  $_SESSION['std_semes'] = $rs['std_semes'];
                                  $_SESSION['userid'] = $rs['std_id'];
                                  $_SESSION['pwd'] = $rs['std_pwd'];
                                  $_SESSION['sta'] = "2";
			}
				else
				{
                                 $_SESSION['m_id'] = $rs['t_id'];
		$_SESSION['t_id'] = $rs['t_id'];
		$_SESSION['teach_name'] = $rs['teach_name']
		$_SESSION['teach_sname'] = $rs['teach_sname'];
		$_SESSION['level_name'] = $rs['level_name'];
		$_SESSION['m_sta'] = $_POST[rdb];
                                $_SESSION['userid'] = $rs['teach_usr'];  //t_id
                                $_SESSION['pwd'] = $rs['teach_pwd'];
                                $_SESSION['sta'] = "1";
		}
		echo "<meta http-equiv=\"refresh\" content=\"0; URL=mainuser.php\">"; // Goto
	}
	else
				{	
		echo "<script>alert('ชื่อผู้ใช้ หรือ รหัสผ่าน ไม่ถูกต้อง');</script>";
		echo "<meta http-equiv=\"refresh\" content=\"0; URL=index.php\">"; // Goto
				}

}
?>
<?
if(isset($_SESSION['sta']))
{
		echo "<div align=center>";
		echo "<dl id=browse>";


		if($_SESSION['sta'] == "2"){
	echo "<dd><img src=images/users1.png>&nbsp;";
echo $_SESSION['std_id'];
		echo "</dd>";
	echo "<dd><img src=images/users1.png>&nbsp;";
		echo $_SESSION['std_name']." ".$_SESSION['std_sname'];
		echo "</dd>";

$da = date("Y-m-d");

		$sqla = "select * from tb_sche where '$da' between sdate and edate ";
		$resa = mysql_query($sqla);
		if(mysql_num_rows($resa) > 0)
			{

$sql1 = "select * from tb_app where app_stuid = '$_SESSION[m_id]'";
$resa = mysql_query($sql1);
$numrow = mysql_num_rows($resa);

if(mysql_num_rows($resa) == 1)
{
	echo "<a href=editappstu.php?std_id=$_SESSION[std_id] target=_blank>แก้ไขใบสมัครรับทุน</a>";
}
else
{
	echo "<a href=app.php?std_id=$_SESSION[std_id] target=_blank>กรอกใบสมัครรับทุน</a>";
}
			}

			echo "<a href=changepwd.php>เปลี่ยนรหัสผ่าน</a>";

		}
		else if($_SESSION['m_sta'] == "1")
		{  
		echo "<dd><img src=images/users1.png>&nbsp;";
		echo $_SESSION['teach_name']." ".$_SESSION['teach_sname'];
		echo "</dd>";

		echo "<BR><BR><a href=appapp.php>พิจารณาใบสมัครรับทุน</a>";
		echo "<a href=changepwd.php>เปลี่ยนรหัสผ่าน</a>";
		}
		echo "<a href=logout.php>ออกจากระบบ</a>";
		echo "</dd></dl></div>";

		 include("menu.php"); 
}
else
{?>
<script language="JavaScript">

function validate(form) {
if(form.userid.value.length < 1){	
    alert("กรุณากรอกชื่อเข้าสู่ระบบ !!!");
form.userid.focus();
    return false;
  }
if(form.pwd.value.length < 1)	{
    alert("กรุณากรอกรหัสผ่าน ให้ถูกต้อง !!!");
form.pwd.focus();
    return false;
  }
	return true;
}
</script>
	<div>
	<dl id="browse">
<form name="form2" method="post" action="menuindex.php"  onSubmit="return validate(this);">
<dt>เข้าสู่ระบบ</dt>
<dd>&nbsp;</dd>
<dd>&nbsp;&nbsp;ชื่อผู้ใช้&nbsp;&nbsp;::&nbsp;&nbsp;&nbsp;<input type="text" name="userid" size="15" class="content" style="BORDER-LEFT: #ACA899 1px solid; BORDER-BOTTOM: #ACA899 1px solid; BORDER-RIGHT: #ACA899 1px solid; BORDER-TOP: #ACA899 1px solid;width=125; FONT-SIZE: 7pt" maxlength="20"></dd>
<dd>&nbsp;&nbsp;รหัสผ่าน&nbsp;&nbsp;::&nbsp;<input type="password" name="pwd" size="15" class="content" style="BORDER-LEFT: #ACA899 1px solid; BORDER-BOTTOM: #ACA899 1px solid; BORDER-RIGHT: #ACA899 1px solid; BORDER-TOP: #ACA899 1px solid;width=125; FONT-SIZE: 7pt" maxlength="20"></dd>
<dd><input type="radio" name="rdb" value="1" checked>&nbsp;อาจารย์</dd>
<dd><input type="radio" name="rdb" value="2">&nbsp;นักศึกษา</dd>
<dd>&nbsp;<div align="center"><input type="Submit" value="เข้าสู่ระบบ" name="submit1"  style="width:55;BORDER-LEFT: #CCCCCC 1px solid; BORDER-BOTTOM: #CCCCCC 1px solid; BORDER-RIGHT: #CCCCCC 1px solid; BORDER-TOP: #CCCCCC 1px solid; FONT-SIZE: 7pt"></div></dd>
<!--<dd><a href="forgetpass.php"><img src=images/users1.png>&nbsp;&nbsp;ลืมรหัสผ่าน</a></dd>-->
</form>				
						</dl>
					</div>
<?}?>