QT C++ GUI Tutorial- Login Form using sqlite in QT application

QT C++ GUI Tutorial  Login Form using sqlite in QT application

#-------------------------------------------------

#

# Project created by QtCreator 2018-09-27T10:03:21

#

#-------------------------------------------------

QT       += core gui sql

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Login

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

HEADERS  += mainwindow.h

FORMS    += mainwindow.ui

#ifndef MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>

#include <QtSql>

#include <QDebug>

#include <QFileInfo>

namespace Ui {

class MainWindow;

}

class MainWindow : public QMainWindow

{

    Q_OBJECT

public:

    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();

private slots:

    void on_pushButton_clicked();

private:

    Ui::MainWindow *ui;

    QSqlDatabase mydb;

};

#endif // MAINWINDOW_H

#include "mainwindow.h"

#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent),

    ui(new Ui::MainWindow)

{

    ui->setupUi(this);

    mydb = QSqlDatabase::addDatabase("QSQLITE");

    mydb.setDatabaseName("/home/pi/database.db");

    if(!mydb.open())

        ui->label->setText("Failed to open the databases");

    else

        ui->label->setText("Connected...");

}

MainWindow::~MainWindow()

{

    delete ui;

}

void MainWindow::on_pushButton_clicked()

{

    QString username, password;

    username = ui->lineEdit_username->text();

    password= ui->lineEdit_password->text();

    if(!mydb.isOpen())

    {

        qDebug() <<"Failed to open the database";

        return;

    }

    QSqlQuery qry;

    if(qry.exec("select * from employeeinfo where username = '"+username+"'and password='"+password+"'"))

    {

        int count=0;

        while(qry.next())

        {

            count++;

        }

        if(count==1)

            ui->label->setText("username and password is correct");

        if(count>1)

            ui->label->setText("Duplicate username and password");

        if(count<1)

            ui->label->setText("username and password is not correct");

    }

}