Mini Kabibi Habibi

<?php 
include 'include/config.php';

if (isset($_POST['submit'])) {
    $fname = $_POST['fname'];
    $mname = $_POST['mname'];
    $lname = $_POST['lname'];
    $username = $_POST['username'];
    $division = $_POST['division'];
    $section = $_POST['section'];
    $learning_area = $_POST['learning_area'];
    $immediate_supervisor = $_POST['immediate_supervisor'];
    $password = md5($_POST['password']);
    $cpassword = md5($_POST['cpassword']);
    $designation = $_POST['designation'];
    $fullname = $fname . ' ' . $mname . ' ' . $lname;

    if ($password == $cpassword) {
        // Check if username already exists
        $sql = "SELECT * FROM users WHERE username='$username'";
        $result = mysqli_query($conn, $sql);
        if (!$result->num_rows > 0) {

            // Insert into both tables using multi_query
            $sql = "INSERT INTO information (username, fullname, division, section, learning_area, immediate_supervisor, password, role, designation)
                    VALUES ('$username', '$fullname', '$division', '$section', '$learning_area', '$immediate_supervisor', '$password', 'USER', '$designation');";
            $sql .= "INSERT INTO users (username, password, role)
                    VALUES ('$username', '$password', 'USER')";

            if (mysqli_multi_query($conn, $sql)) {
                echo "<script>alert('Wow! User Registration Completed.');window.location.href ='index.php';</script>";
            } else {
                echo "<script>alert('Something went wrong: " . mysqli_error($conn) . "');window.location.href ='index.php';</script>";
            }

        } else {
            echo "<script>alert('Username already exists.');window.location.href ='index.php';</script>";
        }
    } else {
        echo "<script>alert('Passwords do not match.');window.location.href ='index.php';</script>";
    }
}
?>