Create session using retrieved data - php

Question

I have a login page where user insert their username and password.
I create a session which will display the username of the user at the main page using below code.
However, instead of the username, I want to display the user's full name. How do I display the full name using $_SESSION['username']?
My table name is users and consist of column fullname, username and password.
if (isset($_POST['login_user'])) {
$username = mysqli_real_escape_string($db, $_POST['username']);
$password = mysqli_real_escape_string($db, $_POST['password']);
if (empty($username)) {
array_push($errors, "Username is required");
}
if (empty($password)) {
array_push($errors, "Password is required");
}
if (count($errors) == 0) {
$password = md5($password);
$query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$results = mysqli_query($db, $query);
if (mysqli_num_rows($results) == 1) {
$_SESSION['username'] = $username;
$_SESSION['success'] = "You are now logged in";
header('location: index.php');
}else {
array_push($errors, "Wrong username/password combination");
}
}
}

Answer 1

Use db query like mysqli_fetch_assoc to get data from db
if (count($errors) == 0) {
$password = md5($password);
$query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$results = mysqli_query($db, $query);
if (mysqli_num_rows($results) == 1) {
$row = mysqli_fetch_assoc($results );
$_SESSION['fullname'] = $row['fullname'];
$_SESSION['username'] = $username;
$_SESSION['success'] = "You are now logged in";
header('location: index.php');
}else {
array_push($errors, "Wrong username/password combination");
}
}
for more : https://www.w3schools.com/php/func_mysqli_fetch_row.asp