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How to Build a Simple Login System with PHP

M66 2025-07-13

How to Build a Simple Login System with PHP

In web development, a login system is one of the most common features. Whether it's for an admin panel, member center, or user account system, login authentication is a vital component. In this article, we will demonstrate how to build a basic login system using PHP, helping developers implement user authentication.

Preparation

Before we begin, ensure that your development environment is correctly set up. You need to have PHP, Apache, and MySQL installed. It is recommended to use an integrated development environment like XAMPP or MAMP for ease of use. Create a project folder and inside it, create a subfolder called “login_system”. We will start by writing the necessary code.

Creating the Database Table

First, we need to set up a database to store user information. In MySQL, create a table named “users” with the following fields:

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

Creating the Login Form Page

Next, we create an HTML file that displays the login form. Below is a simple example of a login page:

<!DOCTYPE html>
<html>
<head>
  <title>Login System</title>
</head>
<body>
  <h2>Welcome to Login</h2>
  <form action="login.php" method="POST">
    <label for="username">Username:</label>
    <input type="text" id="username" name="username" required>
    <label for="password">Password:</label>
    <input type="password" id="password" name="password" required>
    <input type="submit" value="Login">
  </form>
</body>
</html>

Writing the PHP Login Validation Code

Next, create a PHP file named “login.php” that handles the user-submitted login data and validates it. Below is an example of the PHP code:

<?php
// Get the username and password submitted through the form
$username = $_POST['username'];
$password = $_POST['password'];

// Database connection details
$servername = "localhost";
$dbname = "login_system";
$dbusername = "root";
$dbpassword = "";

// Establish a database connection
$conn = new mysqli($servername, $dbusername, $dbpassword, $dbname);

// Check if the connection was successful
if ($conn->connect_error) {
  die("Database connection failed: " . $conn->connect_error);
}

// Query the database to verify user credentials
$sql = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
  echo "Login successful!";
} else {
  echo "Incorrect username or password!";
}

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

Testing the Login System

Once you've completed the code, you can test the login system in your browser. Open your browser and navigate to “http://localhost/login_system/index.html” to access the login page. Enter the correct username and password, and click the “Login” button. The system will validate the input and display the corresponding message.

Conclusion

By following the steps above, you’ve successfully created a simple login system. With this system, users can input their username and password for validation. If you wish to improve it further, consider adding password encryption, session management, and other security features. I hope this guide helps you better understand the process of developing a login system in PHP.

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