private void AddWaiterButton_Click(object sender, EventArgs e)
        {
            EditWaiterForm createForm = new EditWaiterForm();

            createForm.ShowDialog();

            if (createForm.Success)
            {
                var newWaiter = restaurantsDataSet.waiters.NewwaitersRow();
                newWaiter.last_name     = createForm.WaiterLastName;
                newWaiter.first_name    = createForm.WaiterFirstName;
                newWaiter.restaurant_id = RestaurantId;
                newWaiter.earned_money  = 0;
                newWaiter.earned_pants  = 0;

                restaurantsDataSet.waiters.Rows.Add(newWaiter);
                waitersTableAdapter.Update(restaurantsDataSet.waiters);
            }
        }
        private void EditWaiterButton_Click(object sender, EventArgs e)
        {
            var selectedRow = waitersDataGridView.SelectedRows[0];

            EditWaiterForm editForm = new EditWaiterForm
            {
                WaiterLastName  = (string)selectedRow.Cells["last_name"].Value,
                WaiterFirstName = (string)selectedRow.Cells["first_name"].Value
            };

            editForm.ShowDialog();

            if (editForm.Success)
            {
                var waiterRow = restaurantsDataSet.waiters.FindByid((decimal)selectedRow.Cells["id"].Value);
                waiterRow.last_name  = editForm.WaiterLastName;
                waiterRow.first_name = editForm.WaiterFirstName;

                waitersTableAdapter.Update(restaurantsDataSet.waiters);
            }
        }