Question

bool    MainWindow::initDb() {
    db = QSqlDatabase::addDatabase("QSQLITE"); // defined on class header as QSqldatabase db
    db.setDatabaseName("data.db");
    if (!db.open()) {
        QMessageBox::critical(this,
                              tr("Error"),
                              tr("Could not save data. Database problem."));
        return false;
    }
    query.prepare("create table if not exists snippet (id int primary key, title varchar(255) not null, tags varchar(255), snippet text)");
    if (!query.exec()) { // error
        QMessageBox::critical(this,
                              tr("Database error"),
                              tr("Could not setup database"));
        qDebug() << "Database error : " << query.lastError();
        return false;
    }
    query.clear();
    return true;
}

Database It shows Database error message box and the following in the console.

Database error :  QSqlError(-1, "Driver not loaded", "Driver not loaded") 

Answer 1

I got a partial solution. Making query as local object with passing db to it’s constructor solve the problem.
Like

QSqlQuery query(db);