Cant cout the result that what I want with MySQL and c++

#include <iostream>
#include <Windows.h>

#include "jdbc/mysql_connection.h"
#include "jdbc/cppconn/driver.h"
#include "jdbc/cppconn/exception.h"
#include "jdbc/cppconn/resultset.h"
#include "jdbc/cppconn/statement.h"
#include "jdbc/cppconn/prepared_statement.h"

#ifdef _DEBUG
#pragma comment(lib, "debug/mysqlcppconn.lib")
#else
#pragma comment(lib, "mysqlcppconn.lib")
#endif

using namespace std;

std::string Utf8ToMultiByte(std::string utf8_str);

int main()
{
    try
    {
        sql::Driver* driver; 
        sql::Connection* connection; 
        sql::Statement* statement; 
        sql::ResultSet* resultset; 

        driver = get_driver_instance();

        connection = driver->connect("tcp://127.0.0.1:3306", "root", "");

        if (connection == nullptr)
        {
            cout << "connect failed" << endl;
            exit(-1);
        }

        connection->setSchema("logindata");

        statement = connection->createStatement();
        resultset = statement->executeQuery("insert into new_table(number, id, wincount, totalgameplay) values(4, 132, 232349, 123)");
        resultset = statement->executeQuery("select * from new_table ");

        for (;resultset->next();)
        {
            cout << resultset->getInt("id") << " : " <<
                Utf8ToMultiByte(resultset->getString("wincount")) << " : " <<
                Utf8ToMultiByte(resultset->getString("totalgameplay")) << endl;
        }

        delete resultset;
        delete statement;
        delete connection;
    }
    catch (sql::SQLException e)
    {
        cout << "# ERR: SQLException in " << __FILE__;
        cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
        cout << "# ERR: " << e.what();
        cout << " (MySQL error code: " << e.getErrorCode();
        cout << ", SQLState: " << e.getSQLState() << " )" << endl;
    }
    return 0;
}

std::string Utf8ToMultiByte(std::string utf8_str)
{
    std::string resultString; char* pszIn = new char[utf8_str.length() + 1];
    strncpy_s(pszIn, utf8_str.length() + 1, utf8_str.c_str(), utf8_str.length());
    int nLenOfUni = 0, nLenOfANSI = 0; wchar_t* uni_wchar = NULL;
    char* pszOut = NULL;
    // 1. utf8 Length
    if ((nLenOfUni = MultiByteToWideChar(CP_UTF8, 0, pszIn, (int)strlen(pszIn), NULL, 0)) <= 0)
        return nullptr;
    uni_wchar = new wchar_t[nLenOfUni + 1];
    memset(uni_wchar, 0x00, sizeof(wchar_t)*(nLenOfUni + 1));
    // 2. utf8 --> unicode
    nLenOfUni = MultiByteToWideChar(CP_UTF8, 0, pszIn, (int)strlen(pszIn), uni_wchar, nLenOfUni);
    // 3. ANSI(multibyte) Length
    if ((nLenOfANSI = WideCharToMultiByte(CP_ACP, 0, uni_wchar, nLenOfUni, NULL, 0, NULL, NULL)) <= 0)
    {
        delete[] uni_wchar; return 0; 
    }
    pszOut = new char[nLenOfANSI + 1];
    memset(pszOut, 0x00, sizeof(char)*(nLenOfANSI + 1));
    // 4. unicode --> ANSI(multibyte)
    nLenOfANSI = WideCharToMultiByte(CP_ACP, 0, uni_wchar, nLenOfUni, pszOut, nLenOfANSI, NULL, NULL);
    pszOut[nLenOfANSI] = 0;
    resultString = pszOut;
    delete[] uni_wchar;
    delete[] pszOut;
    return resultString;
}

why I cant get result of table information? does insert and select then cout is not proper process?

Also I try with PrepareStatement with above the select phrase. But I worked properly

I know that preparestatement and createstatement is different with dynamic parsing and static parsing. what is more efficient with adding information to database?