使用header（）重定向后会话变量丢失

Question

I have got index.php file that takes username and password from users, then it redirects to process_login.php that compares these credentials with SQL database to authorize the users. Now if the user is authorized, I want to get all the data about this user and want to use in other PHP files. I am using sessions to do so, but somehow they are not working. I know they are so many similar questions, but none of them worked. Here is my process_login.php code

    <?php
  session_start();
  require_once('connectdatabase.php');

if(isset($_POST) && !empty($_POST)) {
  $username = $_POST['username'];
  $password = $_POST['password'];

  $sql = "SELECT * FROM users WHERE USERNAME='$username' AND PASSWORD='$password'";
  $result = mysqli_query($connection, $sql);
  echo $count = mysqli_num_rows($result);

  if($count == 1) {
    $row = mysqli_fetch_assoc($result);
    $_SESSION['first_name'] = $row["FIRST_NAME"];
    $_SESSION['last_name'] = $row["LAST_NAME"];
    $_SESSION['email'] = $row["EMAIL"];
    $_SESSION['username']=$username;
    header('Location: ../../src/welcome.php');
exit();
  }
  else {
    header('Location: ../../src/index.php');
  }
}
?>

Now I want those variables on welcome.php file.

And this is my welcome.php code

<?php
  session_start();
  $fist_name = $_SESSION['first_name'];
  echo "<script>console.log('$first_name');</script>";
?>

Answer 1

It's because you are using $fist_name rather than $first_name. And edit your echo part

<?php
  session_start();
  $fist_name = $_SESSION['first_name'];
  echo "<script>console.log('$first_name');</script>";
?>

To

<?php
  session_start();
  $first_name = $_SESSION['first_name'];
  echo $first_name;
?>