Untitled

<?php
function loginUser() {
    global $connection;

    $username = $_POST['username'];
    $password = $_POST['password'];

    $query = "SELECT * FROM users WHERE userName = '$username' AND userPassword = '$password' ";

    $result = mysqli_query($connection, $query);


} ?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

</head>
<body>

<?php if(isset($_POST['submit'])){ loginUser(); } ?>

    <?php if(!$result){ ?>

        <div class="container">
        <?php echo "<h3 style='color: red;'>Username / Password not found</h3>"; ?>
        </div>

        <?php } else { $row = mysqli_fetch_assoc($result); ?>

        <div class="container">
        <?php echo "<h3 style='color: green;'>Welcome back " . $row['firstName'] . " " . $row['lastName'] . "</h3>"; ?>
        </div>
    <?php } ?>