class SqlWorker : public QObject
{
    Q_OBJECT
public:
    explicit SqlWorker(QObject *parent = nullptr);
    ~SqlWorker ();

    void addDbServer (QString serverName, QHostAddress address);
    QList <QString> getDbServers ();

    QString getLastUsedDbName () { return currentDbName; }
    bool openDbConnection(QString serverName, QString login, QString password);
private:
    QString currentDbName;
    QHash<QString, QHostAddress> dbServers;

    QThread * executorThread;
    SqlQueryExecutor * executor;

signals:
    void stopExecutor ();
    void executorOpenDbConnection (QString, QString, QString, QString);
    void dbErrorOccured (STATE, QString, QString, bool);

private slots:
    void slotHandleDbError (qint8 error, QString errorDescription, QString dbName);
    void slotDbConnected (QString);

};

class SqlQueryExecutor : public QObject
{
    Q_OBJECT
public:
    explicit SqlQueryExecutor(QObject *parent = nullptr);
    ~SqlQueryExecutor ();
private:
    const QString strQueryA618;
    QString strWhereA618;
    A618SqlModel * model618;

    void changeModel618 (const QString& query);

signals:
    void dbConnected (QString);
    void dbDbErrorAppears (qint8 error, QString errorDescription, QString dbName);
    void return618Data (A618SqlModel & model);
    void finished ();

public slots:
    void slotStartExecutorThread ();
    void slotStopExecutorThread ();

    void slotOpenDbConnection (QString adress, QString serverName, QString login, QString password);
    void slotGet618Messages (unsigned int turplesLimit);
};

class A618SqlModel : public QSqlQueryModel
{
    Q_OBJECT

public:
    A618SqlModel(QObject *parent = 0);
    QVariant data(const QModelIndex &index, int role) const;
};

Q_DECLARE_METATYPE(A618SqlModel)

QObject::connect(modelObject, SIGNAL(return618Data(A618SqlModel &)), this, SLOT(slotSet618Messages(A618SqlModel &)));

    qRegisterMetaType<A618SqlModel>();