<form name="login_form" action="login.php" method="post">
    <table width="100%" border="0" cellpadding="0" cellspacing="2">
        <tr>
            <td width="40%">Username</td>
            <td><input type="text" name="login_username" id="login_username" /></td>
        </tr>
        <tr>
            <td>Parola</td>
            <td><input type="password" name="login_password" id="login_password" /></td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td><input type="submit" name="login_btn" value="Login" /></td>
        </tr>
    </table>
</form>
<?php
session_start();
require_once("dbconnect.php");

//  verifica daca exista date transmise
if ($_POST['login_username'] != "" && $_POST['login_password'] != '') {

    // preia datele din formular
    $username = $_POST['login_username'];
    $password = $_POST['login_password'];

    // formeaza si executa query-ul de select din baza de date
    $query = "SELECT * FROM users WHERE 'Username' = '".$username."' AND 'Password' = '".$password."'";
    $result = mysqli_query($connect, $query) or die ( "Error : ". mysqli_error($connect) );

    // verifica daca interogarea mysqli a gasit date valide
    if ($result || mysqli_num_rows($result) < 1) {
        // daca nu, afiseaza un mesaj de eroare
        echo "Datele introduse sunt incorecte<br>
            Click <a href='index.php'>aici</a> pentru a reveni la pagina de login";
    } else {

        // salveaza username-ul si parola in sesiune
        $_SESSION['username'] = $username;
        $_SESSION['password'] = $password;

        // afiseaza un mesaj de succes
        echo "Autentificarea a fost efectuata cu succes.";

    }
    echo $username;
    echo $password;

}
?>