C++ mysql read table

//Utill.h
#ifndef Util_H
#define Util_H

#include <chrono>
#include <ctime>
#include <fstream> 
#include <iostream>
#include "mysql_connection.h"
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
#include <sstream>
#include <stdlib.h>
#include <thread>
#include <unistd.h>
#include <uuid/uuid.h>
#include <vector>

using namespace std;

class Util
{
public:
    static char *uuidValue;
    static char *dtValue;
    char *getTime();
    char *getUuid(); 
    void readSQL5();
};
#endif




//Util.cpp
#include "Model/Util.h"

char *Util::dtValue = (char *)malloc(20);
char *Util::uuidValue = (char *)malloc(40);

void Util::readSQL5()
{
    try
    {
        sql::Driver *driver;
        sql::Connection *conn;
        sql::Statement *stmt;
        sql::PreparedStatement *pstmt;
        sql::ResultSet *res;
        sql::PreparedStatement *tablePstmt;
        sql::ResultSet *tableRes;

        driver = get_driver_instance();
        conn = driver->connect("tcp://127.0.0.1:3306", "root", "password");
        conn->setSchema("db");

        string selectTable = "select table_name from information_schema.tables where table_schema='db'";
        pstmt = conn->prepareStatement(selectTable);
        res = pstmt->executeQuery();

        vector<string> tableVec;
        while (res->next())
        {
            tableVec.push_back(res->getString(1));
        }

        vector<string>::iterator itr = tableVec.begin();
        cout << "Table:";
        while (itr != tableVec.end())
        {
            cout << *itr << "\t";
            itr++;
        }
        cout << endl << endl;

        uint64_t num = 0;
        int loop = 0;
        for (auto &tableName : tableVec)
        { 
            string sql = "select * from " + tableName;
            tablePstmt = conn->prepareStatement(sql);
            tableRes = tablePstmt->executeQuery();
            while (tableRes->next())
            {
                if (++num % 500000 == 0)
                {
                    cout <<"Loop="<<++loop << ",Num=" << num << ",Index=" << tableRes->getInt(1) << ",Id=" << tableRes->getInt64(2)
                         << ",Name=" << tableRes->getString(3) << ",Title=" << tableRes->getString(4) << endl;
                }
            }
            cout << getTime() << ",finished in retrieving from " << tableName << endl<<endl;
        }
        conn->close();
        cout << "IsClosed=" << conn->isClosed() << endl;
        cout << getTime() << ",finished in void Util::readSQL5()!" << endl;
    }
    catch (sql::SQLException &ex)
    {
        cout << "#ERR: SQLException in " << __FILE__ << "," << __FUNCTION__ << "," << __LINE__ << endl;
        cout << ex.what() << endl;
        cout << "Error code:" << ex.getErrorCode() << ",state:" << ex.getSQLState() << endl;
        return;
    }
}

char *Util::getTime()
{
    time_t rawTime = time(NULL);
    struct tm tmInfo = *localtime(&rawTime);
    strftime(dtValue, 20, "%Y%m%d%H%M%S", &tmInfo);
    return dtValue;
}

char *Util::getUuid()
{
    uuid_t newUUID;
    uuid_generate(newUUID);
    uuid_unparse(newUUID, uuidValue);
    return uuidValue;
}

　　

//main.cpp

#include "Model/Util.h"

void readTable5();


int main(int args,char **argv)
{
    try
    {
        readTable5();
    }
    catch(const std::exception& e)
    {
        std::cerr << e.what() << '\n';
    }
    
}

void readTable5()
{
    Util ul;
    ul.readSQL5();
}

Compile:

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

Run

time ./h1 -1;