for(QThread *&threadDB: threadsDB) {
        threadDB = new QThread;
        Worker *worker = new Worker;
        worker->moveToThread(threadDB);

        connect(threadDB, &QThread::finished, worker, &QObject::deleteLater);
        connect(this, &DB::queryWork, worker, &Worker::queryWork);
        connect(this, &DB::workerConnectDB, worker, &Worker::connectDB);
        connect(this, &DB::workerDisconnectDB, worker, &Worker::disconnectDB);
        connect(worker, &Worker::queryResult, this, &DB::queryResult);
        threadDB->start(); }