Noodle/student/header.php

<?php
	$username=$_SESSION['login_user'];
	$sql_query="select full_name from user_info where login = '$username'";
	$name_result=mysqli_query($db,$sql_query);
	$name_res_arr=mysqli_fetch_array($name_result,MYSQLI_ASSOC);
	$full_name=$name_res_arr["full_name"];
?>

<header>
  <div class="container">
    <img src="../img/logo.png" alt="Noodle logo" class="logo">
    <nav>
      <ul>
        <li><a href="/logout.php">Logout</a></li>
      </ul>
    </nav>
  </div>
</header>