cppconn cpp prepared statement insert into table

//model/util.h
#pragma once
#ifndef __util_h__
#define __util_h__
#include <chrono>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
#include <string.h>
#include <unistd.h>
#include <uuid/uuid.h>
#include <vector>
#include <jsoncpp/json/json.h>
#include <cppconn/connection.h>
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/prepared_statement.h>
#include <cppconn/resultset.h>
#include <mysql/mysql.h>

using namespace std;

class util
{
public:
    string get_time_now();
    string get_uuid(); 
    void mysql_prep_stmt_demo();
};

#endif

//model/util.cpp
#include "model/util.h"

std::string util::get_time_now()
{
    chrono::time_point<chrono::high_resolution_clock> now = chrono::high_resolution_clock::now();
    auto ms = chrono::duration_cast<chrono::milliseconds>(now.time_since_epoch()) % 1000;
    time_t rawTime = chrono::high_resolution_clock::to_time_t(now);
    struct tm tmInfo = *localtime(&rawTime);
    stringstream ss;
    ss << std::put_time(&tmInfo, "%Y%m%d%H%M%S") << std::setfill('0') << std::setw(3) << ms.count();
    string dtStr = ss.str();
    ss = stringstream();
    ss.str(std::string());
    return dtStr;
}

std::string util::get_uuid()
{
    uuid_t newUUID;
    uuid_generate(newUUID);
    char *uuidValue = (char *)malloc(40);
    uuid_unparse(newUUID, uuidValue);
    string uuidStr(uuidValue);
    free(uuidValue);
    uuidValue = nullptr;
    return uuidStr;
}

void util::mysql_prep_stmt_demo()
{
    sql::Driver *driver;
    sql::Connection *conn; 
    sql::PreparedStatement *pstmt;
    try
    {
         driver=get_driver_instance();
         conn=driver->connect("tcp://127.0.0.1:3306","username","password");
         conn->setSchema("db");
         pstmt=conn->prepareStatement("insert into b1 (id,author,comment,content,name,title,topic) values (?,?,?,?,?,?,?)");
         for(int i=0;i<1000;i++)
         {
            pstmt->setUInt64(1,static_cast<uint64_t>(i));
            pstmt->setString(2,get_uuid());
            pstmt->setString(3,get_uuid());
            pstmt->setString(4,get_uuid());
            pstmt->setString(5,get_uuid());
            pstmt->setString(6,get_uuid());
            pstmt->setString(7,get_uuid()); 
            pstmt->execute();   
         }  

         delete pstmt;
         delete conn; 
    }
    catch(const std::exception& e)
    {
        std::cerr << e.what() << 'n';
    }
    cout<<get_time_now()<<",finished in "<<__FUNCTION__<<","<<__LINE__<<endl;
}


//main.cpp
#include "model/util.h"
void mysql_prep_stmt_demo()
{
    util ul;
    ul.mysql_prep_stmt_demo();
}

int main(int args,char **argv)
{ 
    mysql_prep_stmt_demo();
}

g++ -g -std=c++2a -I. *.cpp ./model/*.cpp -o h1 -luuid -ljsoncpp -lmysqlcppconn;

./h1

//mysql.sql
//show create table b1 G
Create Table: CREATE TABLE `b1` (
  `idx` int NOT NULL AUTO_INCREMENT,
  `id` bigint NOT NULL DEFAULT '0',
  `author` varchar(40) NOT NULL DEFAULT '',
  `comment` varchar(40) NOT NULL DEFAULT '',
  `content` varchar(40) NOT NULL DEFAULT '',
  `name` varchar(40) NOT NULL DEFAULT '',
  `title` varchar(40) NOT NULL DEFAULT '',
  `topic` varchar(40) NOT NULL DEFAULT '',
  PRIMARY KEY (`idx`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci