How do I code a PHP login?

Login page allows the registered user to access the website and manage its account by entering its username and password.

User SESSION is been created on a successful login attempt.

This helps to detect the user is actually logged in or not when going to other web pages and it also helps to display content according to the user.

In this tutorial, I show how you can create a Login page with PHP and MySQL.

Contents

1. Table structure
2. Configuration
3. HTML
4. CSS
5. PHP
6. Demo
7. Conclusion

1. Table structure

I am using users table in the tutorial example.

CREATE TABLE `users` (
  `id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `username` varchar(80) NOT NULL,
  `name` varchar(80) NOT NULL,
  `password` varchar(80) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

2. Configuration

Create config.php file for database configuration.

Completed Code

<?php
session_start();
$host = "localhost"; /* Host name */
$user = "root"; /* User */
$password = ""; /* Password */
$dbname = "tutorial"; /* Database name */

$con = mysqli_connect($host, $user, $password,$dbname);
// Check connection
if (!$con) {
  die("Connection failed: " . mysqli_connect_error());
}

3. HTML

Create a login page layout that has two input type elements for entering username and password and a button to submit the form.

Completed Code

<div class="container">
    <form method="post" action="">
        <div id="div_login">
            <h2>Login</h2>
            <div>
                <input type="text" class="textbox" id="txt_uname" name="txt_uname" placeholder="Username" />
            </div>
            <div>
                <input type="password" class="textbox" id="txt_uname" name="txt_pwd" placeholder="Password"/>
            </div>
            <div>
                <input type="submit" value="Submit" name="but_submit" id="but_submit" />
            </div>
        </div>
    </form>
</div>

4. CSS

/* Container */
.container{
    width:40%;
    margin:0 auto;
}

/* Login */
#div_login{
    border: 1px solid gray;
    border-radius: 3px;
    width: 470px;
    height: 270px;
    box-shadow: 0px 2px 2px 0px  gray;
    margin: 0 auto;
}

#div_login h2{
    margin-top: 0px;
    font-weight: normal;
    padding: 10px;
    background-color: cornflowerblue;
    color: white;
    font-family: sans-serif;
}

#div_login div{
    clear: both;
    margin-top: 10px;
    padding: 5px;
}

#div_login .textbox{
    width: 96%;
    padding: 7px;
}

#div_login input[type=submit]{
    padding: 7px;
    width: 100px;
    background-color: lightseagreen;
    border: 0px;
    color: white;
}

On the form submit check the username and password entered or not. If entered then execute a SELECT query to count records on the basis of username and password.

If the query returns greater than 0 then initialize $_SESSION['uname'] = $uname and redirect to home.php.

If it returns 0 then display the "Invalid username and password message".

Complete Code

<?php
include "config.php";

if(isset($_POST['but_submit'])){

    $uname = mysqli_real_escape_string($con,$_POST['txt_uname']);
    $password = mysqli_real_escape_string($con,$_POST['txt_pwd']);

    if ($uname != "" && $password != ""){

        $sql_query = "select count(*) as cntUser from users where username='".$uname."' and password='".$password."'";
        $result = mysqli_query($con,$sql_query);
        $row = mysqli_fetch_array($result);

        $count = $row['cntUser'];

        if($count > 0){
            $_SESSION['uname'] = $uname;
            header('Location: home.php');
        }else{
            echo "Invalid username and password";
        }

    }

}

Homepage

Create new home.php file.

First, check whether the user is logged or not by checking the $_SESSION['uname'] variable. If it not set then redirect the user to index.php for login.

Created a logout button that destroy the $_SESSION['uname'] variable and redirect to index.php web page on click.

Complete Code

<?php
include "config.php";

// Check user login or not
if(!isset($_SESSION['uname'])){
    header('Location: index.php');
}

// logout
if(isset($_POST['but_logout'])){
    session_destroy();
    header('Location: index.php');
}
?>
<!doctype html>
<html>
    <head></head>
    <body>
        <h2>Homepage</h2>
        <form method='post' action="">
            <input type="submit" value="Logout" name="but_logout">
        </form>
    </body>
</html>

6. Demo

View Demo

7. Conclusion

In this tutorial, I showed how you can create a simple login page with PHP and MySQL.

You must have to initialize the $_SESSION variable to detect the user when traversing to other pages and destroy it when the user clicks the logout buttons.

If you want to know how to create a register page then you can view the following tutorial.

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