protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {
                if (_dbContext == null)
                {
                    var scope = _scopeFactory.CreateScope();
                    _dbContext = scope.ServiceProvider.GetRequiredService <OnlineExaminationSystemContext>();
                }

                var finishedExams = await _dbContext.Exams
                                    .Where(exam => !exam.IsFinished).ToListAsync();

                foreach (var exam in finishedExams)
                {
                    // bir şeyler yap!
                    exam.IsFinished = true;
                }

                if (_dbContext.ChangeTracker.HasChanges())
                {
                    await _dbContext.SaveChangesAsync();
                }

                _logger.LogInformation("Worker Service is running!");

                await Task.Delay(1000, stoppingToken);
            }
        }