1. reedit the employeeinfo window as

2. modify the employeeinfo.cpp

#include "employeeinfo.h"
#include "ui_employeeinfo.h"
#include "login.h"
#include <QMessageBox>
EmployeeInfo::EmployeeInfo(QWidget *parent) :
    QDialog(parent),ui(new Ui::EmployeeInfo)
{
    ui->setupUi(this);
    if(!login::connOpen())
    {
        ui->label_sec_status->setText("Failed to open the database") ;

    }
    else
    {
        ui->label_sec_status->setText("Connected...") ;

    }
}

EmployeeInfo::~EmployeeInfo()
{
    delete ui;
}

void EmployeeInfo::on_pushButton_clicked()
{

    QString eid,name,surname,age;
    eid = ui->txt_eid->text();
    name =ui->txt_name->text();
    surname = ui->txt_surname->text();
    age = ui->txt_age->text();

    if(!login::connOpen())
    {
        qDebug() << "Failed to open the database";
        return ;
    }

    QsqlQuery qry;

    QString stmt = "insert into employeeinfo (eid,age) values('"+ eid +"','"+ name +"','"+ surname +"','"+ age +"')";
    qry.prepare(stmt);
    if( qry.exec())
    {
        QMessageBox::information(this,tr("Save"),tr("Saved"));
        login::connClose();
    }
    else
    {
        QMessageBox::critical(this,tr("Error"),qry.lastError().text());
    }
}

void EmployeeInfo::on_pushButton_edit_clicked()
{
    QString eid,age;
    eid = ui->txt_eid->text();
    name =ui->txt_name->text();
    surname = ui->txt_surname->text();
    age = ui->txt_age->text();

    if(!login::connOpen())
    {
        qDebug() << "Failed to open the database";
        return ;
    }

    QsqlQuery qry;

    QString stmt = "update employeeinfo set eid='"+ eid+"',name='"+ name+ "',surname='"+ surname+"',age='"+ age +"'where eid='" + eid + "'";
    qry.prepare(stmt);
    if( qry.exec())
    {
        QMessageBox::information(this,tr("Edit"),tr("Updated"));
        login::connClose();
    }
    else
    {
        QMessageBox::critical(this,qry.lastError().text());
    }
}