using session email to fetch user first name in php - php

Question

I have created a session of which a user is using email and password to log in, and the session is capturing his/her email, I want to use the email to fetch her other data like first name and last name, I tried to get it but due to my newbie I ended up getting error, here is my login code:
// LOGIN A USER INTO HIS/HER ACCOUNT
if (isset($_POST['login_user'])) {
$email = mysqli_real_escape_string($db, $_POST['email']);
$password = mysqli_real_escape_string($db, $_POST['password']);
if (empty($email)) {
array_push($errors, "Email is required");
}
if (empty($password)) {
array_push($errors, "Password is required");
}
if (count($errors) == 0) {
$password = md5($password);
$query = "SELECT * FROM users WHERE email='$email' AND password='$password'";
$results = mysqli_query($db, $query);
if (mysqli_num_rows($results) == 1) {
$_SESSION['email'] = $email;
$_SESSION['success'] = "You are now logged in";
header('location: index.php');
}else {
array_push($errors, "Wrong Email or Password combination");
}
}
}
and I figured it to be like the following code below:(which is not actually working)
if($result) {
if(mysqli_num_rows($result) == 1) {
//Login Successful
session_regenerate_id();
$user = mysqli_fetch_assoc($result);
$_SESSION['id'] = $user['user_id'];
$_SESSION['email'] = $user['email'];
$_SESSION['first_name'] = $user['first_name'];
$_SESSION['last_name'] = $user['last_name'];
session_write_close();
header("location: user_index.php");
exit();
else {
$sql = "SELECT first_name FROM users WHERE email = '" .
$_SESSION['email'] . "'";
$result = mysqli_query($sql);
$user = mysqli_fetch_array($result);
echo "Hello, " . $user['first_name']";
}

Answer 1

I found this way to be working, thank you all who tried to help
<?php
include'db.php';
if(isset($_SESSION['email'])){
$query = "SELECT first_name FROM users WHERE email= '".$_SESSION['email']."'";
$result = mysqli_query($db, $query) or
die(mysql_error($db));
if (!$result) die('Query failed: ' . mysqli_error($db));
while($row = mysqli_fetch_array($result)){
echo $row['first_name'];
}
}
?>