QSqlTableModel problem z select()

void QSqlMyTableModel::set_entries()
{
   this->select();
   qDebug() << this->tableName() << lastError();
   qDebug() << "query: " << this->query().isActive();
   qDebug() << "select -> rows: " << rowCount();
   //qDebug() << "select statement: " << selectStatement();

    QSqlQuery q;
    q.exec("SELECT COUNT(*) FROM "+ tableName());
    q.next();
    qDebug() << tableName() << " has: " << q.value(0) << " records";

    _entries.reserve(this->rowCount());
    for(int i = 0; i < this->rowCount(); ++i)
        _entries.push_back(this->record(i));
}

using sqlRecContainer = std::vector<QSqlRecord>;

class QSqlMyTableModel : public QSqlRelationalTableModel
{
    Q_OBJECT
public:
    QSqlMyTableModel() = default;

    auto begin() const
    { return _entries.begin(); }
    auto end() const
    { return _entries.end(); }

    const sqlRecContainer &entries() const
    { return _entries; }
    QSqlRecord get_prototype_record() const;

    template <typename T>
    auto find(const T &field, const QVariant &value) const
    {
        auto rec = std::find_if(_entries.begin(), _entries.end(),
                     [&](const QSqlRecord &rec) { return rec.value(field) == value; });

        return rec != _entries.end() ?
                    std::make_optional<sqlRecContainer::const_iterator>(rec) : std::nullopt;
    }
    template <typename T>
    bool exists(const T &field, const QVariant &value) const
    {
        return find(field, value) ? true : false;
    }
    bool exists(const QSqlRecord &rec, sqlRecContainer::const_iterator hint) const;

    template <typename T>
    bool update(const T &field, const QVariant &old_value, const QVariant &new_value) const
    {
        auto it = find(field, old_value);
        if(!it)
            return false;
        (*it)->value(field) = new_value;
        this->record(std::distance(_entries.begin(), *it)).field(field).setValue(new_value);

        return true;
    }
    void setTable(const QString &tb_name) override;
    QStringList generate_qstrlist(const QString &field_name) const;

    bool push_back_record(std::vector<QVariant> &&values);
    bool push_back_record(QSqlRecord &&new_record);

    bool submit() override;

private:
    sqlRecContainer _entries;
    void set_entries();
    bool insert(QSqlRecord &&rec);
};