<?php
$servername = "localhost";
$username = "root";
$password = "";
$database = "training";

$conn = mysqli_connect($servername, $username, $password, $database);

if($conn = false){
    echo "Error:" . mysqli_connect_error();
}
echo "Done.";
------------------------------------------------------------

<?php
require_once "config.php";

$login_username = $login_password = $confirm_password = "";

if($_SERVER["REQUEST_METHOD"] == "POST"){
    if (mysqli_connect_errno())
{
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
    exit();
}
    $sql = "INSERT INTO users (id,username,password) VALUES (NULL,"."'".$_POST["username"]."', '".$_POST["password"]."')";
    echo $sql;
    $result = $conn->query($sql);

    echo $result;


}
?>