registration.php

<?php
// Include config file
require_once "config2.php";

// Define variables and initialize with empty values
$username = $email = $password = "";
$username_err = $email_err = $password_err = "";


// Processing form data when form is submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {

    // Validate username
    if (empty(trim($_POST["username"]))) {
        $username_err = "Please enter a username.";
    } else {
        $username = trim($_POST["username"]);
    }

    // Validate email
    if (empty(trim($_POST["email"]))) {
        $email_err = "Please enter an email.";
    } else {
        $email = trim($_POST["email"]);
    }

    // Validate password
    if (empty(trim($_POST["password"]))) {
        $password_err = "Please enter a password.";
    } else {
        $password = trim($_POST["password"]);
    }

    // Check input errors before inserting into database
    if (empty($username_err) && empty($email_err) && empty($password_err)) {

        // Prepare an INSERT statement
        $sql = "INSERT INTO users1 (username, email, password) VALUES (?, ?, ?)";

        if ($stmt = $conn->prepare($sql)) {
            // Bind variables to the prepared statement as parameters
            $stmt->bind_param("sss", $param_username, $param_email, $param_password);

            // Set parameters
            $param_username = $username;
            $param_email = $email;
            $param_password = $password;

            // Attempt to execute the prepared statement
            if ($stmt->execute()) {
                 //Redirect to login page
                header("location: login.html");
            } else {
                echo "Something went wrong. Please try again later.";
            }

            // Close statement
            $stmt->close();
        }
    }

    // Close connection
    $conn->close();
}
?>