std::string _dbConnString = "host=" + host + ";user=" + user + ";password=" + password + ";db="+db
    +";compress=true;auto-reconnect=true";


    std::string getkey(int userID, int exchangeID) {
        Poco::Data::MySQL::Connector::registerConnector();

        std::string key;

        {
            // 0. connect & create table
            Session session(Poco::Data::MySQL::Connector::KEY, "host=" + host + ";user=" + user + ";password=" + password +";db=" + db);



            Statement selectn(session);
            selectn << "SELECT key FROM API WHERE user_id=? ", into(api_key), use(userID),  now;

        }
        catch (const Poco::Data::ConnectionFailedException &ce)
        {
            std::cout << ce.displayText() << std::endl;
        }
        catch (const Poco::Data::MySQL::StatementException &se)
        {
            std::cout << se.displayText() << std::endl;
        }


        Poco::Data::MySQL::Connector::unregisterConnector();

        return key;

    }

 std::string getuser(int userID, int exchangeID) {
        Poco::Data::MySQL::Connector::registerConnector();

        std::string user;
    try
        {
            // 0. connect & create table
            Session session(Poco::Data::MySQL::Connector::KEY, "host=" + host + ";user=" + user + ";password=" + password +";db=" + db);



            Statement selectn(session);
            selectn << "SELECT user FROM API WHERE user_id=? ", into(user), use(userID),  now;

        }
        catch (const Poco::Data::ConnectionFailedException &ce)
        {
            std::cout << ce.displayText() << std::endl;
        }
        catch (const Poco::Data::MySQL::StatementException &se)
        {
            std::cout << se.displayText() << std::endl;
        }


        Poco::Data::MySQL::Connector::unregisterConnector();

        return user;

    }

std::string key = getkey(user_id,exchange_id);  //no error
std::string user = getuser(user_id,exchange_id);  //segmentation fault

std::string user = getuser(user_id,exchange_id);  //no error
std::string key = getkey(user_id,exchange_id);  //segmentation fault