private void ControlKeyDown(object sender, KeyEventArgs e)
 {
     try
     {
         if (e.KeyCode == Keys.Enter)
         {
             if (sender == SearchProduct && SearchProduct.EditValue != null)
             {
                 spLength.Focus();
             }
             else if (sender == spPrice)
             {
                 spLength.Focus();
             }
             else if (sender == spLength)
             {
                 spWidth.Focus();
             }
             else if (sender == spWidth)
             {
                 spQuantity.Focus();
             }
             else if (sender == spQuantity)
             {
                 spDiscount.Value = (spPrice.Value * spLength.Value * spWidth.Value * spQuantity.Value) - (int)(spPrice.Value * spLength.Value * spWidth.Value * spQuantity.Value);
                 spDiscount.Focus();
             }
             else if (sender == spDiscount)
             {
                 ProductView.AddNewRow();
                 SearchProduct.EditValue = null;
                 SearchProduct.Focus();
             }
         }
         else if (e.KeyCode == Keys.Delete)
         {
             if (sender == ProductView)
             {
                 if (ProductView.RowCount > 0)
                 {
                     SpInvoiceDiscount.Value = SpInvoiceDiscount.Value - decimal.Parse(ProductView.GetRowCellValue(ProductView.FocusedRowHandle, ProductView.Columns[9]).ToString());
                     spInvoiceTotal.Value    = spInvoiceTotal.Value - decimal.Parse(ProductView.GetRowCellValue(ProductView.FocusedRowHandle, ProductView.Columns[10]).ToString());
                     ProductView.DeleteRow(ProductView.FocusedRowHandle);
                     SearchProduct.Focus();
                 }
             }
         }
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }
 private void btnAddNew_Click(object sender, EventArgs e)
 {
     try
     {
         SearchProduct.Focus();
         DataTable dt = new DataTable();
         dt.Columns.Add(new DataColumn {
             ColumnName = "v1", DataType = typeof(string)
         });                                                                             //PCode
         dt.Columns.Add(new DataColumn {
             ColumnName = "v2", DataType = typeof(string)
         });                                                                             //PName
         dt.Columns.Add(new DataColumn {
             ColumnName = "v3", DataType = typeof(string)
         });                                                                             //UCode
         dt.Columns.Add(new DataColumn {
             ColumnName = "v4", DataType = typeof(string)
         });                                                                             //UName
         dt.Columns.Add(new DataColumn {
             ColumnName = "v5", DataType = typeof(string)
         });                                                                             //Price
         dt.Columns.Add(new DataColumn {
             ColumnName = "v6", DataType = typeof(string)
         });                                                                             //Length
         dt.Columns.Add(new DataColumn {
             ColumnName = "v7", DataType = typeof(string)
         });                                                                             //Width
         dt.Columns.Add(new DataColumn {
             ColumnName = "v8", DataType = typeof(string)
         });                                                                             //Quantity
         dt.Columns.Add(new DataColumn {
             ColumnName = "v9", DataType = typeof(string)
         });                                                                             //Total Quantity
         dt.Columns.Add(new DataColumn {
             ColumnName = "v10", DataType = typeof(string)
         });                                                                              //Discount
         dt.Columns.Add(new DataColumn {
             ColumnName = "v11", DataType = typeof(string)
         });                                                                              //Line Total
         ProductGrid.DataSource  = dt;
         ProductGrid.DataMember  = dt.TableName;
         SpInvoiceDiscount.Value = spInvoiceTotal.Value = spInvoicePaied.Value = 0;
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }