Part 4: Create your own Registration System using PHP and MySql

4. Registering Users with PHP & MySQL

Now we need to create the registration file that will process the form fields, check for basic validation, and insert the new account into our database.

The registration page will require a connection to our database and therefore we must include the necessary variables and MySQL functions. Edit the register.php file and add the following code:

<?php
// Change this to your connection info.
$DATABASE_HOST = 'localhost';
$DATABASE_USER = 'root';
$DATABASE_PASS = '';
$DATABASE_NAME = 'phplogin';
// Try and connect using the info above.
$con = mysqli_connect($DATABASE_HOST, $DATABASE_USER, $DATABASE_PASS, $DATABASE_NAME);
if (mysqli_connect_errno()) {
	// If there is an error with the connection, stop the script and display the error.
	exit('Failed to connect to MySQL: ' . mysqli_connect_error());
}

Don’t forget to update the MySQL variables if your MySQL credentials do not reflect the declared values.

Next, we can add basic validation to ensure the user has entered their details and check for empty variables.

// Now we check if the data was submitted, isset() function will check if the data exists.
if (!isset($_POST['username'], $_POST['password'], $_POST['email'])) {
	// Could not get the data that should have been sent.
	exit('Please complete the registration form!');
}
// Make sure the submitted registration values are not empty.
if (empty($_POST['username']) || empty($_POST['password']) || empty($_POST['email'])) {
	// One or more values are empty.
	exit('Please complete the registration form');
}

Now we need to check if the account already exists in the database. We can check this by selecting a record from our accounts table with the same username that the user has provided.

Add after:

// We need to check if the account with that username exists.
if ($stmt = $con->prepare('SELECT id, password FROM accounts WHERE username = ?')) {
	// Bind parameters (s = string, i = int, b = blob, etc), hash the password using the PHP password_hash function.
	$stmt->bind_param('s', $_POST['username']);
	$stmt->execute();
	$stmt->store_result();
	// Store the result so we can check if the account exists in the database.
	if ($stmt->num_rows > 0) {
		// Username already exists
		echo 'Username exists, please choose another!';
	} else {
		// Insert new account
	}
	$stmt->close();
} else {
	// Something is wrong with the sql statement, check to make sure accounts table exists with all 3 fields.
	echo 'Could not prepare statement!';
}
$con->close();
?>

Replace:

// Insert new account

With:

// Username doesnt exists, insert new account
if ($stmt = $con->prepare('INSERT INTO accounts (username, password, email) VALUES (?, ?, ?)')) {
	// We do not want to expose passwords in our database, so hash the password and use password_verify when a user logs in.
	$password = password_hash($_POST['password'], PASSWORD_DEFAULT);
	$stmt->bind_param('sss', $_POST['username'], $password, $_POST['email']);
	$stmt->execute();
	echo 'You have successfully registered, you can now login!';
} else {
	// Something is wrong with the sql statement, check to make sure accounts table exists with all 3 fields.
	echo 'Could not prepare statement!';
}

This will insert a new account into our accounts table.

Remember in our Login System we used the password_verify function? As you can see in the code above we use the password_hash function, this will encrypt the user’s password using the one-way algorithm — this will prevent your users passwords from being exposed if for somehow your database becomes vulnerable.

That’s basically all we need to do to register accounts on our website.