Quick Qtwidget application connect to Mysql database

dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"
#include <iostream>
#include <QSqlDriver>
#include <QSqlDatabase>
#include <QtSql>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
}

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

void Dialog::on_pushButton_clicked()
{
    if(connectDatabase() == true){
        qDebug() << "Success";
    }
}

bool Dialog::connectDatabase(){
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    QSqlQuery query;

    db.setHostName("localhost");
    db.setUserName("root");
    db.setPassword("root");
    db.setDatabaseName("inventory");


    if(db.open()){
       // QMessageBox :: warning(this,"login","Successful Database Connection");
        qDebug()<<"True";
        return true;


    }else{
        //QMessageBox :: warning(this,"login","Failed Database Connection");
        qDebug()<<"Haiconnect Buda";
        return false;
    }

}

dialog.h

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();

private slots:
    void on_pushButton_clicked();

private:
    Ui::Dialog *ui;
    bool connectDatabase();
};

#endif // DIALOG_H

dialog.pro

#-------------------------------------------------
#
# Project created by QtCreator 2017-04-06T16:12:35
#
#-------------------------------------------------

QT       += core gui sql

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Inventory_Remodeled
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += main.cpp\
        mainwindow.cpp \
    dialog.cpp

HEADERS  += mainwindow.h \
    dialog.h

FORMS    += mainwindow.ui \
    dialog.ui

main.cpp

#include "mainwindow.h"
#include "dialog.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
//    MainWindow w;
    Dialog d;
    d.show();
//    w.show();

    return a.exec();
}