Database is not connecting with php

Question

I am trying to make a registration system with php and mysql. I am attempting to connect the database to the system and am getting errors which I do not understand.

I'm not 100% sure stackoverflow have put my image in so i'll describe it as best I can. The error reads: Warning: mysqli_connect(): The server requested authentication method unknown to the client [caching_sha2_password] in C:\wamp\www\registration\server.php on line 5

I am relatively new to both php and my sql so any advice would be great.

Answer 1

For example:

generatesalt.php (optional, for safety)

function generateSalt()
    {
        $salt = '';
        $saltLength = 8;
        for($i=0; $i<$saltLength; $i++) {
            $salt .= chr(mt_rand(33,126)); //character from ASCII-table
        }
        return $salt;
    }

db.php

$dbname = 'test';
$localhost = 'localhost';
$login = 'root';
$pass = '';

$link = @mysqli_connect($localhost, $login, $pass, $dbname);

if (!$link) {
    echo "Problem, error code: " . mysqli_connect_errno();
    exit;
}

reg.php (This example is not very secure. I advise you to use PDO. This is an easy example for understanding.)

require_once 'db.php';
require_once 'generateSalt.php';

if ( !empty($_POST['login']) and !empty($_POST['password']) and !empty($_POST['password_confirm']) ) {
        $login = $_POST['login'];
        $password = $_POST['password'];
        $password_confirm = $_POST['password_confirm']; 


if ($password == $password_confirm) {

    $query = 'SELECT*FROM user WHERE login="'.$login.'"';
            $is_login_free = mysqli_query($link, $query);
            $login_free = mysqli_fetch_assoc($is_login_free);

    if (empty( $login_free)) {

        $salt = generateSalt();
        $saltedpassword = md5($password.$salt);  

        $query = "INSERT INTO `user` (`login`, `password`, `salt`) VALUES ('$login', '$saltedpassword', '$salt')";
        $result = mysqli_query($link, $query);

        echo 'You have successfully registered';
        echo '<br>';
        echo 'Sign in: <a href="/login.php">Click</a>';
        echo '<br>';
        echo 'Home: <a href="/">Click</a>';
    } else {
        echo 'The login is busy';
    }

} else {
    echo 'Passwords do not match';
}
} else {
    header("Location: /");
    exit();
}

Form

<h1>Sign up</h1>
<form action="/reg.php" method="post">
    <input type="text" name="login" required><br>
    <input type="password" name="password" required><br>
    <input type="password" name="password_confirm" required><br><br>
    <input type="submit" value="Create an account">
</form>