public void writeToDB(List<Person> personList){
        Connection con = null;
        Statement stmt = null;
        PreparedStatement preparedStatement = null;
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            con = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:xe","admin","admin");

            stmt=con.createStatement();
            if(!stmt.isClosed()){
                logger.info("Connection established : 127.0.0.1:1521:xe;admin;admin");
            }
            for(Person p : personList){
                if(!isExistPersonInDB(con, p)){
                    preparedStatement = con.prepareStatement("INSERT INTO PERSON (NAME, AGE, GENDER, RELATIONSHIPSTATUS, COMMUNICATIONSKILL, PLACEHASH) VALUES(?,?,?,?,?, ?)");
                    preparedStatement.setString(1, p.getName());
                    preparedStatement.setInt(2, p.getAge());
                    preparedStatement.setString(3, String.valueOf(p.getGender()));
                    preparedStatement.setString(4, String.valueOf(p.getRelationshipStatus()));
                    preparedStatement.setDouble(5, p.getCommunicationSkill());
                    preparedStatement.setString(6, p.getPlaceHash());
                    preparedStatement.executeQuery();
                    logger.trace("Insert " + p.toString() + " to DB.");
                }

                if(!isExistPlaceInDB(con, p.getPlace())){
                    preparedStatement = con.prepareStatement("INSERT INTO PLACE(name, iscity, iscrowded, isday, hashcode) VALUES(?,?,?,?,?)");
                    preparedStatement.setString(1, p.getPlace().getName());
                    preparedStatement.setString(2, String.valueOf(p.getPlace().isCity()));
                    preparedStatement.setString(3, String.valueOf(p.getPlace().isCrowded()));
                    preparedStatement.setString(4, String.valueOf(p.getPlace().isDay()));
                    preparedStatement.setString(5, String.valueOf(p.getPlace().hashCo()));
                    preparedStatement.executeQuery();
                    logger.trace("Insert place " + p.getPlaceHash() + " to DB.");
                }

            }
        } catch (ClassNotFoundException e) {
            logger.warn(e.getMessage());
        } catch (SQLException e) {
            logger.warn(e.getMessage());
        }finally {
            try {
                if(preparedStatement != null){
                    preparedStatement.close();
                }
                if(stmt != null){
                    stmt.close();
                }

                if(con != null){
                    con.close();
                }

                if(con.isClosed()) logger.info("Connection is closed.");
            } catch (SQLException e) {
                logger.warn(e.getMessage());
            }
        }
    }

public boolean isExistPersonInDB(Connection connection, Person person){
        try {
             PreparedStatement preparedStatement = connection.prepareStatement("select count(*)\n" +
                    "from person\n" +
                    "where name = ? AND age = ? AND placehash = ?");
            preparedStatement.setString(1, person.getName());
            preparedStatement.setInt(2, person.getAge());
            preparedStatement.setString(3, person.getPlaceHash());
            ResultSet resultSet = preparedStatement.executeQuery();


            resultSet.next();
            int countRecords = resultSet.getInt(1);

            if(resultSet != null){
                resultSet.close();
            }

            if(preparedStatement != null){
                preparedStatement.close();
            }

            //connection will be closed in main method ???
            if (countRecords != 0) {
                logger.trace("Person is not added, it exists in DB : " + person.toString());
                return true;
            }
        } catch (SQLException e) {
            logger.warn(e.getMessage() + " isExistPersonInDB");
        }


        return false;
    }

    public boolean isExistPlaceInDB(Connection connection, Place place) {
        try {
            Statement st = connection.createStatement();
            ResultSet resultSet = st.executeQuery("SELECT COUNT(*) FROM PLACE WHERE HASHCODE = '" + place.hashCo() + "'");
            resultSet.next();
            int countRecords = resultSet.getInt(1);

            if(resultSet != null){
                resultSet.close();
            }

            if(st != null){
                st.close();
            }

            //connection will be closed in main method ?????
            if (countRecords != 0) {
                logger.trace("Place is not added, it exists in DB : " + place.hashCo());
                return true;
            }
        } catch (SQLException e) {
            logger.warn(e.getMessage() + " isExistPlaceInDB");
        }
        return false;
    }