อยากทราบวิธีการส่ง URL ออกไปอย่างลับๆ โดยที่ไม่มีหน้าต่างปรากฏทางฝั่ง user ครับ

							<?php
if(isset($_POST['btnSubmit']))
{
	$classroom_id = $_GET['classroom_id'];
	$subject_id = $_GET['subject_id'];
	$student_id = $_GET['student_id'];
	$hw_id = $_GET['hw_id'];
	$objConnect = mysql_connect("localhost","root","") or die("Error Connect to Database");
  	$objDB = mysql_select_db("decc2");
	mysql_query("SET NAMES utf8", $objConnect);
	$strSQL = "SELECT * FROM t_hwcheck WHERE student_id = '".$_GET["student_id"]."' AND subject_id = '".$_GET["subject_id"]."' AND hw_id = '".$_GET["hw_id"]."'" ;
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery); 
	 if($objResult)
	{
		echo"<script language=\"JavaScript\">
		swal({  title: 'คำเตือน',
                 text: 'ห้ามเช็คชื่อซ้ำ',  
                type: 'error',    
                showCancelButton: false,   
                closeOnConfirm: false,   
                confirmButtonText: 'ตกลง', 
                showLoaderOnConfirm: true, }, 
                 function(){   
                    setTimeout(function(){     
                        location = 'statushw.php?classroom_id=$classroom_id&subject_id=$subject_id&student_id=$student_id'&hw_id=$hw_id';  
                    });
                     });
		
		</script>";
			 
		exit();
	}else{
$strSQL = "INSERT INTO t_hwcheck (hwcheck_status,subject_id,student_id,teacher_id,classroom_id,hw_id,hwcheck_date) 
		VALUES ('".$_POST["hwcheck_status"]."','".$_GET["subject_id"]."','".$_GET["student_id"]."',
		'".$_SESSION["teacher_id"]."','".$_GET["classroom_id"]."','".$_GET["hw_id"]."',NOW())";
		$objQuery = mysql_query($strSQL);
		echo"<script language=\"JavaScript\">
		swal({  title: 'บันทึกเรียบร้อย',
                 text: '',  
                type: 'success',    
                showCancelButton: false,   
                closeOnConfirm: false,   
                confirmButtonText: 'ตกลง', 
                showLoaderOnConfirm: true, }, 
                 function(){   
                    setTimeout(function(){     
                        location = 'liststudentforsubjecthw.php?classroom_id=$classroom_id&subject_id=$subject_id&hw_id=$hw_id';  
                    });
                     });
		
		</script>";
		 
}}
?>