private void addEmployee_Click(object sender, EventArgs e)
        {
            AddEditEmployeeForm f = new AddEditEmployeeForm(trainingGroupsManager);

            if (f.ShowDialog() == DialogResult.OK)
            {
                UpdateEmployeeDataGrid();
            }
        }
        private void editEmployeeButton_Click(object sender, EventArgs e)
        {
            if (employeesDataGrid.SelectedRows.Count == 0)
            {
                MessageBox.Show("Сотрудник не выбран.");
                return;
            }

            AddEditEmployeeForm f = new AddEditEmployeeForm(trainingGroupsManager, trainingGroupsManager.GetEmpById(
                                                                Convert.ToInt32(employeesDataGrid.SelectedRows[0].Cells[0].Value)));

            if (f.ShowDialog() == DialogResult.OK)
            {
                UpdateEmployeeDataGrid();
            }
        }