private void ButtonAdd_Click(object sender, RoutedEventArgs e)
        {
            //Open a new window adding a new office staff
            ClassEmployee             employee = new ClassEmployee();
            WindowEmployeeDataEdition windowEmployeeDataEdition = new WindowEmployeeDataEdition(employee);

            windowEmployeeDataEdition.AddNew = true;
            bool update = (bool)windowEmployeeDataEdition.ShowDialog();

            if (update)
            {
                UpdateEmployee(employee, windowEmployeeDataEdition.AddNew);
                LoadDataToDataGrid();
            }
        }
        private void ButtonEdit_Click(object sender, RoutedEventArgs e)
        {
            //Check if user selected doctor
            if (DataGridListOfEmployee.SelectedIndex == -1)
            {
                MessageBox.Show("Select the row corresponding to the employee", "No row selected");
                return;
            }
            //Open a new window editing existing doctor
            ClassEmployee             employee = (ClassEmployee)DataGridListOfEmployee.SelectedItem;
            WindowEmployeeDataEdition windowEmployeeDataEdition = new WindowEmployeeDataEdition(employee);

            windowEmployeeDataEdition.AddNew = false;
            bool update = (bool)windowEmployeeDataEdition.ShowDialog();

            if (update)
            {
                UpdateEmployee(employee, windowEmployeeDataEdition.AddNew);
                LoadDataToDataGrid();
            }
        }