<?php
    $connection = new mysqli("localhost","root","rootroot","login_db");

    if($connection){
        echo("<p>Conexão a base de dados realiza com sucesso!</p>");
    }else{
        echo("<p>Algo não está a funcionar...</p>");
    }

    $username = $_POST["username"];
    $password = $_POST["password"];

    $queryUser = $connection->query("SELECT username FROM logins WHERE (username = '$username')");
    $resultUser = $queryUser->fetch_assoc();
    $queryPass = $connection->query("SELECT password FROM logins WHERE (password = '$password')");
    $resultPass = $queryPass->fetch_assoc();

    if($username = $resultUser["username"]){
        if($password = $resultPass["password"]){
          echo("<center><h1 style='font-family:arial'>Parabéns, <u>" . $resultUser["username"] . "</u>.<br>Login realizado com sucesso!</h1><center>");
        }else{
            echo("<p>Password errada.</p>");
        }
    }else{
        echo("Nome de utilizador inexistente!");
    }
?>