I just reinstalled QT because the debugger was simply not working to only find out that now the database connector is not working anymore. I did not change anything in the code regarding the connector and yet, it fails to connect me to the database.

This is the header:

// databaseconnector.h
#ifndef DATABASECONNECTOR_H
#define DATABASECONNECTOR_H

#include <QObject>
#include <QSqlDatabase>
#include <QSqlQuery>

class DatabaseConnector : public QObject
{
    Q_OBJECT

public:
    explicit DatabaseConnector(QObject *parent = nullptr);
    ~DatabaseConnector();

    bool connectToDatabase(const QString &serverName, const QString &dbName);
    void disconnectFromDatabase();
    QSqlDatabase getDatabase(){return m_database;};
private:
    QSqlDatabase m_database;

    bool openConnection();
    void closeConnection();
};

#endif // DATABASECONNECTOR_H

And this is the source file:

// databaseconnector.cpp
#include "databaseconnector.h"
#include <QDebug>
#include<QSqlError>

DatabaseConnector::DatabaseConnector(QObject *parent) : QObject(parent)
{
}

DatabaseConnector::~DatabaseConnector()
{
    disconnectFromDatabase();
}

bool DatabaseConnector::connectToDatabase(const QString &serverName, const QString &dbName)
{
    qDebug()<<serverName;
    qDebug()<<dbName;
    m_database = QSqlDatabase::addDatabase("QODBC");
    QString dsn = QString("DRIVER={SQL Server};SERVER=%1;DATABASE=%2;Trusted_Connection=Yes;").arg(serverName).arg(dbName);
    m_database.setDatabaseName(dsn);

    return openConnection();
}

void DatabaseConnector::disconnectFromDatabase()
{
    closeConnection();
}

bool DatabaseConnector::openConnection()
{
    if (m_database.isOpen())
        return true;

    if (m_database.open()) {
        qDebug() << "Connected to database successfully!";
        return true;
    } else {
        qDebug() << "Error connecting to database:" << m_database.lastError().text();
        return false;
    }
}

void DatabaseConnector::closeConnection()
{
    if (m_database.isOpen()) {
        m_database.close();
        qDebug() << "Disconnected from database";
    }
}

This is where I instantiate the connection with the database. Everything is the way I left it before reinstalling QT, I did not change a single word. The server name of the database is correct, the name of the database is correct.

MainWindow::MainWindow(C_User* user, QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    // Încearcă să te conectezi la baza de date
    if (m_dbConnector.connectToDatabase(R"(DESKTOP-RTLB2TISQLEXPRESS)", "Formula1nou")) {
        qDebug() << "Connected to database successfully!";
    } else {
        qDebug() << "Failed to connect to database!";
    }

    // Inițializează interfața utilizatorului
    ui->setupUi(this);
    this->user = user;

    // Configurări suplimentare
    ui->toolBar->setMovable(false);

    centerWindow(this);
}

The error I get:

Error connecting to database: "[Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified [Microsoft][ODBC Driver Manager] Invalid connection string attribute, IM002;01S00 QODBC: Unable to connect"

Thank you in advance for any help!