In this tutorial, you will learn how to perform login action with Google Account using PHP, MySQLi, and Google OAuth API.

Follow the below steps to create this Login Application

First of all, you must have the Google OAuth 2.0 Client Secret and Client ID.

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Creating Application Files & Folders

After getting the client id and client secret, now we will create our application files & folders.

So, go to your XAMPP htdocs folder or www directory and create a new folder called google_login

Now, go inside the google_login folder, but before going to creating files, you have to download the Google APIs Client Library for PHP.

Extract the Google APIs Zip file and rename it to google-api.

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google_login folder structure

<?php
require 'google-api/vendor/autoload.php';

// Creating new google client instance
$client = new Google_Client();

// Enter your Client ID
$client->setClientId('YOUR_CLIENT_ID');
// Enter your Client Secrect
$client->setClientSecret('YOUR_CLIENT_SECRECT');
// Enter the Redirect URL
$client->setRedirectUri('http://localhost/google_login/login.php');

// Adding those scopes which we want to get (email & profile Information)
$client->addScope("email");
$client->addScope("profile");


if(isset($_GET['code'])):

    $token = $client->fetchAccessTokenWithAuthCode($_GET['code']);
    $client->setAccessToken($token['access_token']);

    // getting profile information
    $google_oauth = new Google_Service_Oauth2($client);
    $google_account_info = $google_oauth->userinfo->get();

    // showing profile info
    echo "<pre>";
    var_dump($google_account_info);

else: 
    // Google Login Url = $client->createAuthUrl(); 
?>

    <a class="login-btn" href="<?php echo $client->createAuthUrl(); ?>">Login</a>

<?php endif; ?>

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Saving profile information in the Database & making login action

Start your MySQL server or start phpMyAdmin and create a new Database called – google_login

After creating the database now use the following SQL code to create users table & the structure of the users table.

CREATE TABLE `users` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `google_id` varchar(150) COLLATE utf8mb4_unicode_ci NOT NULL,
 `name` varchar(50) COLLATE utf8mb4_unicode_ci NOT NULL,
 `email` varchar(50) COLLATE utf8mb4_unicode_ci NOT NULL,
 `profile_image` text COLLATE utf8mb4_unicode_ci NOT NULL,
 PRIMARY KEY (`id`),
 UNIQUE KEY `google_id` (`google_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

<?php
session_start();
session_regenerate_id(true);
// change the information according to your database
$db_connection = mysqli_connect("localhost","root","","google_login");
// CHECK DATABASE CONNECTION
if(mysqli_connect_errno()){
    echo "Connection Failed".mysqli_connect_error();
    exit;
}

<?php
require 'db_connection.php';

if(isset($_SESSION['login_id'])){
    header('Location: home.php');
    exit;
}

require 'google-api/vendor/autoload.php';

// Creating new google client instance
$client = new Google_Client();

// Enter your Client ID
$client->setClientId('YOUR_CLIENT_ID');
// Enter your Client Secrect
$client->setClientSecret('YOUR_CLIENT_SECRECT');
// Enter the Redirect URL
$client->setRedirectUri('http://localhost/google_login/login.php');

// Adding those scopes which we want to get (email & profile Information)
$client->addScope("email");
$client->addScope("profile");


if(isset($_GET['code'])):

    $token = $client->fetchAccessTokenWithAuthCode($_GET['code']);

    if(!isset($token["error"])){

        $client->setAccessToken($token['access_token']);

        // getting profile information
        $google_oauth = new Google_Service_Oauth2($client);
        $google_account_info = $google_oauth->userinfo->get();
    
        // Storing data into database
        $id = mysqli_real_escape_string($db_connection, $google_account_info->id);
        $full_name = mysqli_real_escape_string($db_connection, trim($google_account_info->name));
        $email = mysqli_real_escape_string($db_connection, $google_account_info->email);
        $profile_pic = mysqli_real_escape_string($db_connection, $google_account_info->picture);

        // checking user already exists or not
        $get_user = mysqli_query($db_connection, "SELECT `google_id` FROM `users` WHERE `google_id`='$id'");
        if(mysqli_num_rows($get_user) > 0){

            $_SESSION['login_id'] = $id; 
            header('Location: home.php');
            exit;

        }
        else{

            // if user not exists we will insert the user
            $insert = mysqli_query($db_connection, "INSERT INTO `users`(`google_id`,`name`,`email`,`profile_image`) VALUES('$id','$full_name','$email','$profile_pic')");

            if($insert){
                $_SESSION['login_id'] = $id; 
                header('Location: home.php');
                exit;
            }
            else{
                echo "Sign up failed!(Something went wrong).";
            }

        }

    }
    else{
        header('Location: login.php');
        exit;
    }
    
else: 
    // Google Login Url = $client->createAuthUrl(); 
?>

    <a class="login-btn" href="<?php echo $client->createAuthUrl(); ?>">Login</a>

<?php endif; ?>

<?php
require 'db_connection.php';

if(!isset($_SESSION['login_id'])){
    header('Location: login.php');
    exit;
}

$id = $_SESSION['login_id'];

$get_user = mysqli_query($db_connection, "SELECT * FROM `users` WHERE `google_id`='$id'");

if(mysqli_num_rows($get_user) > 0){
    $user = mysqli_fetch_assoc($get_user);
}
else{
    header('Location: logout.php');
    exit;
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title><?php echo $user['name']; ?></title>
    <style>
        *,
        *::before,
        *::after {
            box-sizing: border-box;
            -webkit-box-sizing: border-box;
        }
        body{
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background-color: #f7f7ff;
            padding: 10px;
            margin: 0;
        }
        ._container{
            max-width: 400px;
            background-color: #ffffff;
            padding: 20px;
            margin: 0 auto;
            border: 1px solid #cccccc;
            border-radius: 2px;
        }

        ._img{
            overflow: hidden;
            width: 100px;
            height: 100px;
            margin: 0 auto;
            border-radius: 50%;
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
        }
        ._img > img{
            width: 100px;
            min-height: 100px;
        }
        ._info{
            text-align: center;
        }
        ._info h1{
            margin:10px 0;
            text-transform: capitalize;
        }
        ._info p{
            color: #555555;
        }
        ._info a{
            display: inline-block;
            background-color: #E53E3E;
            color: #fff;
            text-decoration: none;
            padding:5px 10px;
            border-radius: 2px;
            border: 1px solid rgba(0, 0, 0, 0.1);
        }
    </style>
</head>
<body>
    <div class="_container">
        <div class="_img">
            <img src="<?php echo $user['profile_image']; ?>" alt="<?php echo $user['name']; ?>">
        </div>
        <div class="_info">
            <h1><?php echo $user['name']; ?></h1>
            <p><?php echo $user['email']; ?></p>
            <a href="logout.php">Logout</a>
        </div>
    </div>
</body>
</html>

<?php
// Initialize the session.
// If you are using session_name("something"), don't forget it now!
session_start();

// Unset all of the session variables.
$_SESSION = array();

// If it's desired to kill the session, also delete the session cookie.
// Note: This will destroy the session, and not just the session data!
if (ini_get("session.use_cookies")) {
    $params = session_get_cookie_params();
    setcookie(session_name(), '', time() - 42000,
        $params["path"], $params["domain"],
        $params["secure"], $params["httponly"]
    );
}

// Finally, destroy the session.
session_destroy();
header("Location: login.php");
exit;
?>

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Now test the application. Open – http://localhost/google_login/login.php