2 different user session

PHP
7

yess exactly, this session is for USER A

<?php
   session_start();
   

						  $link=mysqli_connect("localhost","root",'',"sysp");
						if($link===false)
						{
						 die("error cant connect".mysqli_connect_error());
						}
					   $user_check = $_SESSION['login_user'];  // what it is 
					   
					   $ses_sql = mysqli_query($link,"select email from user where email = '$user_check' ");
					   
					   $row = mysqli_fetch_array($ses_sql,MYSQLI_ASSOC);
					   
					   $login_session = $row['email'];
					   
					   if(!isset($_SESSION['login_user']))
					   {
						header("location:login.php");
					   }
?>

this is for User B

<?php
   session_start();
	  if($_SERVER["REQUEST_METHOD"] == "POST") {
      $link=mysqli_connect("localhost","root",'',"sysp");
	if($link===false)
	{
	 die("error cant connect".mysqli_connect_error());
	}
   $user_check = $_SESSION['login_user'];
   
   $ses_sql = mysqli_query($link,"select email from ngo where email = '$user_check' ");
   
   $row = mysqli_fetch_array($ses_sql,MYSQLI_ASSOC);
   
   $login_session = $row['email'];
   
   if(!isset($_SESSION['login_user'])){
      header("location:wrong.php");
   }
	  }
?>