✅ How to Create a Login System in PHP (Step-by-Step with Code)

🔹 Introduction

Creating a login system is one of the most common and essential features of any web application. In this tutorial, you’ll learn how to build a simple and secure login system using PHP and MySQL.

Whether you're a beginner or refreshing your skills, this step-by-step guide will help you understand the core concepts behind user authentication.

🔧 Technologies Used:

PHP
MySQL (phpMyAdmin)
HTML & CSS (Basic)

📂 Folder Structure

/login-system
├── db.php
├── login.php
├── welcome.php
├── logout.php

🛠 Step 1: Create the Database and Table

Open phpMyAdmin and run the following SQL query:


CREATE DATABASE login_demo;

USE login_demo;

CREATE TABLE users (
  id INT(11) AUTO_INCREMENT PRIMARY KEY,
  username VARCHAR(50) NOT NULL,
  password VARCHAR(255) NOT NULL
);

Now insert a test user:


INSERT INTO users (username, password) 
VALUES ('admin', MD5('admin123'));

🛠 Step 2: Create Database Connection (db.php)


$host = "localhost";
$user = "root";
$password = "";
$database = "login_demo";

$conn = mysqli_connect($host, $user, $password, $database);

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
?>

🛠 Step 3: Create Login Form (login.php)


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

$error = '';

if (isset($_POST['login'])) {
    $username = $_POST['username'];
    $password = md5($_POST['password']); // MD5 encryption

    $query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
    $result = mysqli_query($conn, $query);

    if (mysqli_num_rows($result) == 1) {
        $_SESSION['username'] = $username;
        header("Location: welcome.php");
    } else {
        $error = "Invalid username or password!";
    }
}
?>

<!DOCTYPE html>
<html>
<head>
    <title>PHP Login System</title>
</head>
<body>
    <h2>Login Form</h2>
    <form method="post">
        <input type="text" name="username" required placeholder="Username"><br><br>
        <input type="password" name="password" required placeholder="Password"><br><br>
        <button type="submit" name="login">Login</button>
    </form>
    <p style="color:red;"><?php echo $error; ?></p>
</body>
</html>

🛠 Step 4: Welcome Page (welcome.php)


<?php
session_start();
if (!isset($_SESSION['username'])) {
    header("Location: login.php");
    exit();
}
?>

<!DOCTYPE html>
<html>
<head>
    <title>Welcome</title>
</head>
<body>
    <h2>Welcome, <?php echo $_SESSION['username']; ?>!</h2>
    <a href="logout.php">Logout</a>
</body>
</html>

🛠 Step 5: Logout (logout.php)


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

✅ Conclusion

You’ve now built a working login system using PHP and MySQL!
In a real-world project, you should use password hashing (password_hash) instead of MD5 for better security.

Next steps:

Add registration page
Use password_hash() and password_verify()
Implement "remember me" functionality

🔗 Related Posts (for interlinking):

How to connect PHP with MySQL database
PHP CRUD tutorial for beginners
PHP form validation step-by-step

📌 SEO Keywords You Can Use (for Blogger)

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