private void searchButton_Click(object sender, EventArgs e)
        {
            try
            {
                String price1 = price1TextBox.Text;
                String price2 = price2TextBox.Text;

                if (String.IsNullOrEmpty(price1) || String.IsNullOrEmpty(price2))
                {
                    MessageBox.Show("Insert price range!");
                    return;
                }
                List <Mobile> mobiles = _mobileManager.SearchMobileByPrice(price1, price2);
                if (mobiles != null)
                {
                    showMobileGridView.Columns.Clear();
                    showMobileGridView.Columns.Add("SerialNumber", "SI#");
                    showMobileGridView.DataSource = mobiles;
                }
                else
                {
                    showMobileGridView.Columns.Clear();
                    MessageBox.Show("No Data found!!");
                    return;
                }
            }
            catch (Exception exception)
            {
                MessageBox.Show(exception.Message);
                _mobileManager.CloseConnection();
            }
        }