Creating a PHP User Authentication System

In this tutorial, we will create a simple PHP user authentication system. This system will include user registration, login, and logout functionalities. Let's break down the steps:

Step 1: Create a Database

Create a MySQL database to store user information. Use the following SQL query:

        CREATE DATABASE IF NOT EXISTS mydatabase;
    

Step 2: Create a Users Table

Create a table to store user data within the database:

        CREATE TABLE IF NOT EXISTS users (
            id INT AUTO_INCREMENT PRIMARY KEY,
            username VARCHAR(255) NOT NULL,
            password VARCHAR(255) NOT NULL
        );
    

Step 3: HTML Form for Registration

Create an HTML form for user registration:

        <form action="register.php" method="post">
            <label for="username">Username:</label>
            <input type="text" name="username" required>
            <label for="password">Password:</label>
            <input type="password" name="password" required>
            <button type="submit">Register</button>
        </form>
    

Step 4: PHP Script for User Registration

Create a PHP script (register.php) to handle user registration:

        <?php
        // Connect to the database
        $conn = new mysqli("localhost", "username", "password", "mydatabase");
        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        }
        // Process registration form data
        if ($_SERVER["REQUEST_METHOD"] == "POST") {
            $username = $_POST["username"];
            $password = password_hash($_POST["password"], PASSWORD_DEFAULT);
            $sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
            if ($conn->query($sql) === TRUE) {
                echo "Registration successful!";
            } else {
                echo "Error: " . $sql . "
" . $conn->error;
            }
        }
        // Close the database connection
        $conn->close();
        ?>
    

This is a basic example to get you started. It's important to enhance security, handle errors, and implement features like password hashing, session management, and more for a production environment.