PHP PDO Connection and Authentication(Registration, Login and Logout)

Connection String:

Please add this to config.php

<?php
session_start();
// Define database
define('dbhost', 'localhost');
define('dbuser', 'root');
define('dbpass', '');
define('dbname', 'db_name');
// Connecting database
try {
    $connect = new PDO("mysql:host=" . dbhost . "; dbname=" . dbname, dbuser, dbpass);
    $connect->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch(PDOException $e) {
    echo $e->getMessage();
}
?>

Registration:

<?php
require 'config.php';
if (isset($_POST['register'])) {
    $errMsg = '';
    // Get data from FROM
    $parentname = $_POST['parentname'];
    $mobileno = $_POST['mobileno'];
    $password = $_POST['password'];
    $email = $_POST['email'];
    try {
        $stmtuser = $connect->prepare('SELECT * FROM tbl_users WHERE user_mobile = :mobile');
        $stmtuser->execute(array(':mobile' => $mobileno,));
        $datauser = $stmtuser->fetch(PDO::FETCH_ASSOC);
        //exit;
        if (empty($datauser)) {
            $stmt = $connect->prepare('INSERT INTO tbl_users (user_name, user_pass, user_mobile, user_email) VALUES (:user_name, :user_pass, :user_mobile, :user_email)');
            $stmt->execute(array(':user_name' => $parentname, ':user_pass' => $password, ':user_mobile' => $mobileno, ':user_email' => $email,));
            date_default_timezone_set('Etc/UTC');
            $stmtuser = $connect->prepare('SELECT * FROM tbl_users WHERE user_mobile = :mobile');
            $stmtuser->execute(array(':mobile' => $mobileno,));
            $datauser = $stmtuser->fetch(PDO::FETCH_ASSOC);
            $_SESSION['user_name'] = $datauser['user_name'];
            $_SESSION['user_id'] = $datauser['id'];
            $_SESSION['user_mobile'] = $datauser['user_mobile'];
            $_SESSION['role'] = $datauser['role'];
            $_SESSION['status'] = $datauser['status'];
            echo '<script>window.location.replace("index.php")</script>';
            exit;
        } else {
            $stmt = $connect->prepare('UPDATE tbl_users set user_name = :user_name, user_pass = :user_pass, user_email = :user_email where user_mobile = :user_mobile');
            $stmt->execute(array(':user_name' => $parentname, ':user_pass' => $password, ':user_mobile' => $mobileno, ':user_email' => $email,));
            $stmtuser = $connect->prepare('SELECT * FROM tbl_users WHERE user_mobile = :mobile');
            $stmtuser->execute(array(':mobile' => $mobileno,));
            $datauser = $stmtuser->fetch(PDO::FETCH_ASSOC);
            $_SESSION['user_name'] = $datauser['user_name'];
            $_SESSION['user_id'] = $datauser['id'];
            $_SESSION['user_mobile'] = $datauser['user_mobile'];
            $_SESSION['role'] = $datauser['role'];
            $_SESSION['status'] = $datauser['status'];
            echo '<script>window.location.replace("index.php")</script>';
            exit;
        }
    }
    catch(PDOException $e) {
        echo $e->getMessage();
    }
}
if (isset($_GET['action']) && $_GET['action'] == 'joined') {
    $successMsg = 'Registration successful Now you can <a href="/">login</a>';
}
?>

Login :

<?php
require 'config.php';
if (!empty($_SESSION['user_id'])) {
    header('Location: index.php');
}
if (isset($_POST['login'])) {
    $errMsg = '';
    // Get data from FORM
    $mobile = $_POST['mobile'];
    $password = $_POST['password'];
    if ($mobile == '') $errMsg = 'Enter mobile no';
    if ($password == '') $errMsg = 'Enter password';
    if ($errMsg == '') {
        try {
            $stmt = $connect->prepare('SELECT * FROM tbl_users WHERE user_mobile = :mobile && user_pass = :pass && otp_verification = :verification');
            $stmt->execute(array(':mobile' => $mobile, ':pass' => $password, ':verification' => 1,));
            $data = $stmt->fetch(PDO::FETCH_ASSOC);
            if ($data == false) {
                $errMsg = "User $mobile not found.";
            } else {
                if ($password == $data['user_pass']) {
                    $_SESSION['user_name'] = $data['user_name'];
                    $_SESSION['user_id'] = $data['id'];
                    $_SESSION['user_mobile'] = $data['user_mobile'];
                    $_SESSION['role'] = $data['role'];
                    $_SESSION['status'] = $data['status'];
                    header('Location: index.php');
                    exit;
                } else {
                    $errMsg = 'Password not match.';
                }
            }
        }
        catch(PDOException $e) {
            $errMsg = $e->getMessage();
        }
    } else {
        $errMsg = 'Error in Logging In.';
    }
}
?>

Logout :

<?php
require 'config.php';
session_destroy();
header('Location: index.php');
?>

Also read:

PDO CRUD Operations