Also ich hab das Login system mal nachgebaut aber ich bekomme immer ne mysql fehler meldung, die ich mir überhaupt net erklären kann 
hier noch die fehler meldung die kommt wenn ich mich einloggen will:
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /srv/www/htdocs/web91/html/sadn/sadn/die3/login.php on line 15
Warning: Cannot modify header information - headers already sent by (output started at /srv/www/htdocs/web91/html/sadn/sadn/die3/login.php:15) in /srv/www/htdocs/web91/html/sadn/sadn/die3/login.php on line 30
mfg dark_544

PHP:
<?php
// Session starten
session_start ();
include("connection.php");
$sql = "SELECT ".
"id, nickname, e-mail, vorname ".
"FROM ".
"user ".
"WHERE ".
"(nickname like '".$_REQUEST["name"]."') AND ".
"(passwort = '".md5 ($_REQUEST["pwd"])."')";
$result = mysql_query ($sql);
if (mysql_num_rows ($result) > 0)
{
// Benutzerdaten in ein Array auslesen.
$data = mysql_fetch_array ($result);
// Sessionvariablen erstellen und registrieren
$_SESSION["user_id"] = $data["id"];
$_SESSION["user_nickname"] = $data["nickname"];
$_SESSION["user_e-mail"] = $data["e-mail"];
$_SESSION["user_vorname"] = $data["vorname"];
header ("Location: indexint.php");
}
else
{
header ("Location: index.php");
}
?>
hier noch die fehler meldung die kommt wenn ich mich einloggen will:
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /srv/www/htdocs/web91/html/sadn/sadn/die3/login.php on line 15
Warning: Cannot modify header information - headers already sent by (output started at /srv/www/htdocs/web91/html/sadn/sadn/die3/login.php:15) in /srv/www/htdocs/web91/html/sadn/sadn/die3/login.php on line 30
mfg dark_544