Building a Simple Login System with PHP and MySQL 🚀

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Building a Simple Login System with PHP and MySQL 🚀

Every website needs user authentication, whether it’s for a dashboard, admin panel, or member-only content. In this guide, you’ll learn how to build a secure login system in PHP using MySQL, sessions, and password hashing.

🎯 What You’ll Learn:

✅ How to create a user registration system
✅ How to store passwords securely (using password_hash())
✅ How to handle user login & logout
✅ How to use sessions to keep users logged in

Let’s get started! 🚀

1️⃣ Setting Up the Database

Before we start coding, let’s create the database and users table.

Run this SQL command:

CREATE DATABASE zeroexp_dev;
USE zeroexp_dev;

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50) UNIQUE NOT NULL,
    email VARCHAR(100) UNIQUE NOT NULL,
    password VARCHAR(255) NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

🔥 What happens?

  • The users table stores username, email, and hashed password.
  • The password column is VARCHAR(255) because hashed passwords are long.

2️⃣ Database Connection File (db.php)

We’ll use PDO to connect PHP to MySQL.

db.php

<?php
$host = "localhost";
$dbname = "zeroexp_dev";
$username = "root";
$password = "";

try {
    $pdo = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $username, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("Database connection failed: " . $e->getMessage());
}
?>

🔥 Why use PDO?
✅ More secure than mysqli_connect()
✅ Supports prepared statements (prevents SQL injection)

3️⃣ User Registration (Signup)

Users need to register first before logging in.

register.php

<?php
require "db.php";

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = trim($_POST["username"]);
    $email = trim($_POST["email"]);
    $password = password_hash($_POST["password"], PASSWORD_BCRYPT); // Hash password

    $stmt = $pdo->prepare("INSERT INTO users (username, email, password) VALUES (?, ?, ?)");
    
    if ($stmt->execute([$username, $email, $password])) {
        echo "Registration successful! <a href='login.php'>Login here</a>";
    } else {
        echo "Error registering user!";
    }
}
?>

<form method="post">
    Username: <input type="text" name="username" required><br>
    Email: <input type="email" name="email" required><br>
    Password: <input type="password" name="password" required><br>
    <input type="submit" value="Register">
</form>

🔥 Why use password_hash()?

  • Stores passwords securely instead of plain text.
  • Uses bcrypt encryption, making it almost impossible to crack.

4️⃣ User Login (Authentication)

Once users register, they can log in.

login.php

<?php
session_start();
require "db.php";

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = trim($_POST["username"]);
    $password = trim($_POST["password"]);

    $stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
    $stmt->execute([$username]);
    $user = $stmt->fetch(PDO::FETCH_ASSOC);

    if ($user && password_verify($password, $user["password"])) {
        $_SESSION["username"] = $username; // Store user session
        header("Location: dashboard.php");
    } else {
        echo "Invalid credentials!";
    }
}
?>

<form method="post">
    Username: <input type="text" name="username" required><br>
    Password: <input type="password" name="password" required><br>
    <input type="submit" value="Login">
</form>

🔥 What happens?
✅ password_verify() compares the hashed password from the database.
✅ If login is successful, we store the username in a session.
✅ If login fails, the user sees an error message.

5️⃣ Creating a Dashboard (Protected Page)

Now, let’s create a dashboard that only logged-in users can access.

dashboard.php

<?php
session_start();
if (!isset($_SESSION["username"])) {
    echo "Access denied! <a href='login.php'>Login here</a>";
    exit;
}

echo "Welcome, " . $_SESSION["username"] . "! <a href='logout.php'>Logout</a>";
?>

🔥 What happens?
✅ If no session exists, access is denied.
✅ Logged-in users see a welcome message.

6️⃣ Logout System

Users should be able to log out safely.

logout.php

<?php
session_start();
session_unset();
session_destroy();
header("Location: login.php");
?>

🔥 What happens?
✅ session_unset() removes all session data.
✅ session_destroy() ends the session.
✅ The user is redirected to the login page.

🎯 Mini Project: User Authentication System

Now, let’s combine everything into a fully functional login system.

File Purpose
db.php Connects PHP to MySQL
register.php Handles user registration
login.php Processes login requests
dashboard.php Displays user dashboard (requires login)
logout.php Logs users out

✅ What You’ve Built

✔️ Users can register with a secure password
✔️ Users can log in with hashed passwords
✔️ Logged-in users can access a private dashboard
✔️ Users can securely log out

🚀 Boom! You now have a secure login system in PHP!

🚀 Final Thoughts

Now you know how to:
✅ Store passwords securely with password_hash()
✅ Authenticate users safely
✅ Use sessions to manage logins
✅ Build a simple login system in PHP

👉 Next: Pagination in PHP

Happy coding! 🎉🚀

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