&lt;?php

$mysql = mysqli_connect("localhost", "root", "", "lazowski");

if (isset($_POST['login']) ) {
    $login = $_POST['login'];
    $haslo = $_POST['haslo'];

    $query = mysqli_query($mysql, "select * from uzytkownicy where login = \"" . $login . "\" and haslo = \"".md5($haslo)."\";");
    
    if(mysqli_fetch_array($query))
    {
        echo "Zalogowano";
        mysqli_query($mysql, "update uzytkownicy set data_ost_log=NOW() where login = \"" . $login . "\"");
    } else {
        echo "Błędne dane";
    }
}

mysqli_close($mysql);
?&gt;

<!DOCTYPE html>
&lt;html&gt;
&lt;head&gt;
    &lt;title&gt;Formularz logowania&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    <h2>Logowanie</h2>
    &lt;form method="post" acti&gt;
        Login: &lt;input type="text" name="login"&gt;&lt;br>
        Hasło: &lt;input type="haslo" name="haslo"&gt;&lt;br>
        &lt;input type="submit" value="Zaloguj"&gt;
    &lt;/form&gt;
&lt;/body&gt;
&lt;/html&gt;