ถ้าผมจะทำเวปคล้ายๆกับ youtube จะเป็นต้องใส่ session ในหน้า index ด้วยหรือเปล่าครับ

<?
	session_start();
	if($_SESSION['UserID'] == "")
	{
		echo "Please Login!";
		exit();
	}

	if($_SESSION['Status'] != "USER")
	{
		echo "This page for User only!";
		exit();
	}	
	
	mysql_connect("localhost","root","root");
	mysql_select_db(".......");
	$strSQL = "SELECT * FROM signup WHERE UserID = '".$_SESSION['UserID']."' ";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);
?>

session_start();

$User=$_POST['User'];
$Password=$_POST['Password'];

$Result=mysql_query("SELECT * FROM member WHERE User='".$User."' AND Password='".$Password."'")
$Check=mysql_num_rows($Result);

if($Check != 0){

$_SESSION['User']=$User;
$_SESSION['Password']=$Password;
 ?>              
             <script language="javascript">
	alert('ยินดีต้อนรับสู่ระบบ');
	window.location='index.php';
	</script>
<? }else{ ?>
                <script language="javascript">
	alert('User นี้ไม่มีอยู่ในระบบ');
	window.location='index.php';
	</script>
<? } ?>

<?php ob_start(); ?>
<?
session_start();
mysql_connect("localhost","root","1234");
mysql_select_db("projectblack");
$strSQL = "SELECT * FROM signup WHERE Username = '".trim($_POST['txtUsername'])."' 
and Password = '".trim($_POST['txtPassword'])."'"; //?????????????? login
$objQuery = mysql_query($strSQL);
$objResult = mysql_fetch_array($objQuery);
if(!$objResult)
{
echo "Username and Password ???????!"; 
print "<meta http-equiv=refresh content=3;URL=login1.php>"; 
}
else
{
$_SESSION["UserID"]=$objResult["UserID"];
$_SESSION["Status"]=$objResult["Status"];

session_write_close();

if($objResult["Status"]=="USER")

header("location:welcome_user_page.php"); 
}
mysql_close();
?>

<?php ob_start(); 
 
session_start(); 
mysql_connect("localhost","root","1234"); 
mysql_select_db("projectblack"); 

$User=$_POST['txtUsername'];
$Password=$_Post['txtPassword']

$strSQL =mysql_query( "SELECT * FROM signup WHERE Username ='".$User."' AND Password='".$Password."'") or die (mysql_error()); 

$objResult=mysql_fetch_array($strSQL);

if($objResult){
$_SESSION['UserID']=$objResult['UserID']; 
$_SESSION['Status']=$objResult['Status']; 
   
  if($_SESSION['Status']!=""){
   header("location:welcome_user_page.php");  
   }

}else{
 
echo 'User นี้ไม่มีอยู่ในระบบ';

}

 

?>