protected String doInBackground(String... params) {
    String type = params[0];
    String login_url = "xxxx/login.php"; //URL to login script
    String register_url = "xxxx/hvzregister.php"; //URL to register script
    String update_url ="xxxx/update.php"; //URL to update script
    String team_url ="xxxx/teaminsert.php"; //URL to team script;
    URL url; //URL
    HttpURLConnection httpURLConnection; //Http connection with via URL
    OutputStream outputStream; //Stream for sending out data
    BufferedWriter bufferedWriter; //Writes out data
    String post_data; //The data to post
    InputStream inputStream; //Stream for receiving data
    BufferedReader bufferedReader; //Read data in
    String result = "";
    String line = "";
    if (type.equals("Login")) {
        try {
            String user_name = params[1];
            String password = params[2];
            url = new URL(login_url);
            httpURLConnection = (HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            outputStream = httpURLConnection.getOutputStream();
            bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
            post_data = URLEncoder.encode("user_name", "UTF-8")+"="+URLEncoder.encode(user_name, "UTF-8")+"&"
                    +URLEncoder.encode("password", "UTF-8")+"="+URLEncoder.encode(password, "UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            inputStream = httpURLConnection.getInputStream();
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
            while ((line = bufferedReader.readLine()) != null) {
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    } else if (type.equals("register")) {
        try {
            String username = params[1];
            String password = params[2];
            String email = params[3];
            url = new URL(register_url);
            httpURLConnection = (HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            outputStream = httpURLConnection.getOutputStream();
            bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
            post_data = URLEncoder.encode("username", "UTF-8")+"="+URLEncoder.encode(username, "UTF-8")+"&"
                    + URLEncoder.encode("password", "UTF-8")+"="+URLEncoder.encode(password, "UTF-8")+"&"
                    + URLEncoder.encode("email", "UTF-8")+"="+URLEncoder.encode(email, "UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            inputStream = httpURLConnection.getInputStream();
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
            while ((line = bufferedReader.readLine()) != null) {
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    } else if(type.equals("update")) {
        try {
            String latitude = params[1];
            String longitude = params[2];
            url = new URL(update_url);
            httpURLConnection = (HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            outputStream = httpURLConnection.getOutputStream();
            bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
            post_data = URLEncoder.encode("latitude", "UTF-8")+"="+URLEncoder.encode(latitude, "UTF-8")+"&"
                    +URLEncoder.encode("longitude", "UTF-8")+"="+URLEncoder.encode(longitude, "UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            inputStream = httpURLConnection.getInputStream();
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
            while ((line = bufferedReader.readLine()) != null) {
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

public void onLocationChanged(Location location) {
    double longitude = location.getLongitude();
    double latitude = location.getLatitude();
    String str_latitude = Double.toString(latitude);
    String str_longitude = Double.toString(longitude);
    String str_un = AppConstraints.sharedPreference.getValue(getApplicationContext(), AppConstraints.USERNAME_PREF, AppConstraints.USERNAME_KEY);

    String type = "update";
    BackgroundWorker backgroundWorker = new BackgroundWorker(this);
    backgroundWorker.execute(type, str_un, str_latitude, str_longitude);
}

<?php
require "conn.php";

$username = $_GET["username"];

$latitude = $_POST["latitude"];
$longitude = $_POST["longitude"];

$float_lat = floatval($latitude);

$float_lon = floatval($longitude);



$sql_update = "UPDATE player SET latitude = '$latitude', longitude =
              '$longitude' WHERE ((username) = '$username')";


$result = mysql_query($conn, $sql_update);

if ($result) {
    echo "Table updated";
}
else {
    echo "Error";
}
?>