private void okButton_Click(object sender, EventArgs e)
        {
            DateTime guaranteeEnd, entryDate;

            TsEntity db = new TsEntity();

            try
            {
                guaranteeEnd = Convert.ToDateTime(guaranteeTextBox.Text);
                entryDate    = Convert.ToDateTime(entryDateTextBox.Text);
            }
            catch (Exception exception)
            {
                MessageBox.Show("Введите дату в формате дд.мм.гггг", "Ошибка", MessageBoxButtons.OK,
                                MessageBoxIcon.Error);
                return;
            }

            var name         = nameTextBox.Text;
            var serialNumber = Convert.ToInt32(serialNumberTextBox.Text);

            var seller      = sellerComboBox.Text;
            var type        = typeComboBox.Text;
            var globalType  = globalTypeComboBox.Text;
            var price       = priceTextBox.Text;
            var placement   = placementComboBox.Text;
            var responsible = responsibleComboBox.Text;
            var id          = 0;

            //using (SqlConnection connection = new SqlConnection(connectionString))
            //{
            //    var command = new SqlCommand();
            //    command.CommandType = CommandType.Text;
            //    command.CommandText = string.Format(@"insert into dbo.devices(deviceName, serialNumber, guaranteeEnd, seller, type, entryDate, price, placement, responsible)
            //                         values (N'{0}', {1}, {2}, {3}, {4}, {5}, {6}, {7}, {8})",
            //                            name, serialNumber, guaranteeEnd, seller, type, entryDate, price, placement, responsible);
            //    connection.Open();
            //    command.ExecuteNonQuery();
            //    connection.Close();
            //db.SaveChanges();



            switch (Text)
            {
            case "Добавить устройство":
                if (type == "ПК" || type == "Ноутбук" || type == "Моноблок" || globalType == "Устройство")
                {
                    db.devices.Add(new devices()
                    {
                        deviceName   = name,
                        serialNumber = serialNumber,
                        guaranteeEnd = guaranteeEnd,
                        seller       = seller,
                        type         = type,
                        entryDate    = entryDate,
                        price        = price,
                        placement    = placement,
                        responsible  = responsible
                    });
                    db.SaveChanges();
                }

                if (type == "Мышь" || type == "Клавиатура" || type == "Геймпад" || type == "Аудио-система" ||
                    globalType == "Комплектующее")
                {
                    db.device_accessories.Add(new device_accessories()
                    {
                        accessoryName = name,
                        serialNumber  = serialNumber,
                        guaranteeEnd  = guaranteeEnd,
                        seller        = seller,
                        type          = type,
                        entryDate     = entryDate,
                        price         = price,
                        placement     = placement,
                        responsible   = responsible
                    });
                    db.SaveChanges();
                }

                break;

            case "Редактировать устройство":
                id = Convert.ToInt32(db.devices.Where(it => it.deviceName == name).FirstOrDefault().id);
                db.UpdateDeviceForSupport(id, name, serialNumber, guaranteeEnd, seller, type, entryDate, price,
                                          placement, responsible);
                break;

            case "Редактировать комплекктующее к устройству":
                id = Convert.ToInt32(db.device_accessories.Where(it => it.accessoryName == name)
                                     .FirstOrDefault().id);
                db.UpdateAccessoryForSupport(id, name, serialNumber, guaranteeEnd, seller, type, entryDate,
                                             price, placement, responsible);
                break;

            default:
                return;
            }

            this.Close();
        }