public void addQuizRating(double rating) {
		raterNumber++;
		totalRating += rating;
		try {
			String statement = new String("UPDATE " + DBTable + " SET "
					+ "raternumber=raternumber+1, rating=rating+?"
					+ " WHERE qid=?");
			PreparedStatement stmt = DBConnection.con.prepareStatement(statement);
			stmt.setDouble(1, rating);
			stmt.setInt(2, quizID);
			stmt.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		}			
	}