@Override
	public double findCustomersBalance(int id) {
		double customersBalance = 0;
		
		String sql = "SELECT balance FROM customer WHERE customer_id='" + id + "';";
		
		Connection con = null;
		try {
			con = getConnection();
			PreparedStatement statement = con.prepareStatement(sql);
			ResultSet resultSet = statement.executeQuery();
			if(resultSet.next()) {
				customersBalance = resultSet.getDouble("balance");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			if (con != null) closeConnection(con);
		}
		
		return customersBalance;
	}