private void insertOrder() throws SQLException {
PreparedStatement prep = conn.prepareStatement("insert into orders(customer_id , total) values(?, ?)");
prep.setInt(1, random.nextInt(getCustomerCount()));
BigDecimal total = new BigDecimal("0");
prep.setBigDecimal(2, total);
prep.executeUpdate();
ResultSet rs = prep.getGeneratedKeys();
rs.next();
int orderId = rs.getInt(1);
int lines = random.nextInt(20);
for (int i = 0; i < lines; i++) {