// Try to connect
    $conn = mysqli_connect($host, $dbuser, $pass, $db) or  die('Could not connect !<br />Please contact the site\'s administrator.');
    $db = mysqli_select_db($conn, $db) or  die('Could not connect to database !<br />Please contact the site\'s administrator.');

    $query = sprintf("
    SELECT username
    FROM Users
    WHERE
    username = '%s' and password = '%s'", mysqli_real_escape_string($conn, sha1($_POST["username"])), mysqli_real_escape_string($conn, sha1($_POST["password"])));

    $result = mysqli_query($conn, $query);

    if (mysqli_num_rows($result) == 1) {

        echo ("err_20192");
    }
    else {

      echo("err_2O192");
    }

    mysqli_close($conn);