public static final String READINGS_CREATE = "CREATE TABLE 'readings' ('building_id' TEXT NOT NULL , "
            + "'position_id' TEXT NOT NULL , 'x' FLOAT NOT NULL, 'y' FLOAT NOT NULL, "
            + " 'ssid' TEXT NOT NULL , 'mac_id' TEXT NOT NULL , 'rssi' INTEGER NOT NULL )";

    public ArrayList<String> getPositions(String building_id) {
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery("select distinct position_id from "
                        + READINGS_TABLE + " where building_id=?",
                new String[] { building_id });
        ArrayList<String> result = new ArrayList<String>();
        cursor.moveToFirst();
        while (cursor.isAfterLast() == false) {
            result.add(cursor.getString(0));
            cursor.moveToNext();
        }
        return result;
    }

    public boolean addReadings(String building_id, PositionData positionData) {
        Log.v("Just Before db : ", positionData.toString());
        deleteReading(building_id, positionData.getName());

        SQLiteDatabase db = getWritableDatabase();
        for (Map.Entry<String, Integer> e : positionData.getValues().entrySet()) {
            ContentValues cv = new ContentValues();
            cv.put("building_id", building_id);
            cv.put("position_id", positionData.getName());
            cv.put("ssid",positionData.routers.get(e.getKey()));
            cv.put("mac_id",e.getKey());
            cv.put("rssi", e.getValue());
            cv.put("x", positionData.getX());
            cv.put("y", positionData.getY());
            Log.v(e.getKey(), e.getValue().toString());
            db.insert(READINGS_TABLE, null, cv);

        }
        System.out.println("Adding done");
        return true;

    }