ถามเรื่อง SESSION หน่อยครับ ผมทำถูกใหมครับ เรื่องของการวาง SESSION

<?
    require_once "connectdb.php";
	$strSQL = "SELECT * FROM admin WHERE Username = '".mysql_real_escape_string($_POST['username'])."' 
	and Password = '".mysql_real_escape_string($_POST['password'])."'";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);
	if(!$objResult)
	{
			 echo "<script language='javascript'>alert('Invalid username & password');</script>";
			 echo "<meta http-equiv='refresh' content='0;URL=index.php'>";
	}
	else
	{
			$_SESSION["id"] = $objResult["id"];
			$_SESSION["Status"] = $objResult["Status"];

			session_write_close();
			
			if($objResult["Status"] == "Admin")
			{
				echo "<meta http-equiv='refresh' content='0;URL=admin_page.php'>";
				
			}
			else if ($objResult["Status"] == "Teacher")
			{
				echo "<meta http-equiv='refresh' content='0;URL=teacher_page.php'>";
			}
			else if ($objResult["Status"] == "Student")
			{
				echo "<meta http-equiv='refresh' content='0;URL=student_page.php'>";
			}
	}
	mysql_close();
?>