<?php

// Hier mysql_connect, mysql_select_db, am besten includen

/* if(isset($_GET["APIKey"]) && !empty($_GET["APIKey"]))
{
    // Tu was auch immer ..
} else {
    // Kein APIKey übergeben
} */

if( isset($_GET["username"], $_GET["password"])
    && !empty($_GET["username"])
    && !empty($_GET["password"]))
{
    $username = mysql_real_escape_string($_GET["username"]);
    $password = mysql_real_escape_String($_GET["password"]); // ggf. ersetzen durch z.B. -> $password = md5($_GET["password"]);

    $query = mysql_query("SELECT id, username, gang, rank, isleader FROM users WHERE username='" . $username . "' AND password='" . $password . "'"); // or die(mysql_error());

    if(mysql_num_rows($query) > 0)
    {
        $assoc = mysql_fetch_assoc($query);
        echo json_encode($assoc);
    } else {
        echo json_encode(array("id"=>-1));
    }
}