private DbHelper() {
        try {
            Class.forName(driver);
            if (login.equals("")) {
                conn = DriverManager.getConnection(url);
            } else {
                conn = DriverManager.getConnection(url, login, password);
            }
            logger.info("Connection OK!");

            if (!isTablesExist()) {
                Statement stmt = conn.createStatement();
                String createSql = readResource(DbHelper.class, "create_tables.sql");
                stmt.executeUpdate(createSql);

                String insertSql = readResource(DbHelper.class, "insert.sql");
                stmt.executeUpdate(insertSql);

                stmt.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(0);
        }
    }