private void DataGridView2_RowHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
 {
     try
     {
         DataGridViewRow dr = DataGridView2.SelectedRows[0];
         this.Hide();
         frmSales frmSales = new frmSales();
         // or simply use column name instead of index
         // dr.Cells["id"].Value.ToString();
         frmSales.Show();
         frmSales.txtInvoiceNo.Text = dr.Cells[0].Value.ToString();
         frmSales.dtpInvoiceDate.Text = dr.Cells[1].Value.ToString();
         frmSales.txtSubTotal.Text = dr.Cells[2].Value.ToString();
         frmSales.txtTaxPer.Text = dr.Cells[3].Value.ToString();
         frmSales.txtTaxAmt.Text = dr.Cells[4].Value.ToString();
         frmSales.txtDiscountPer.Text = dr.Cells[5].Value.ToString();
         frmSales.txtDiscountAmount.Text = dr.Cells[6].Value.ToString();
         frmSales.txtTotal.Text = dr.Cells[7].Value.ToString();
         frmSales.txtTotalPayment.Text = dr.Cells[8].Value.ToString();
         frmSales.txtPaymentDue.Text = dr.Cells[9].Value.ToString();
         frmSales.txtRemarks.Text = dr.Cells[10].Value.ToString();
         frmSales.btnUpdate.Enabled = true;
         frmSales.Delete.Enabled = true;
         frmSales.btnPrint.Enabled = true;
         frmSales.Save.Enabled = false;
         con = new SqlConnection(cs.DBConn);
         con.Open();
         cmd = new SqlCommand("SELECT Product.ProductID,ProductSold.Productname,ProductSold.Price,ProductSold.Quantity,ProductSold.TotalAmount from Invoice_Info,ProductSold,Product where Invoice_info.InvoiceNo=ProductSold.InvoiceNo and Product.ProductID=ProductSold.ProductID and invoice_Info.InvoiceNo='" + dr.Cells[0].Value.ToString() + "'", con);
         rdr = cmd.ExecuteReader();
         while (rdr.Read() == true)
         {
             ListViewItem lst = new ListViewItem();
             lst.SubItems.Add(rdr[0].ToString().Trim());
             lst.SubItems.Add(rdr[1].ToString().Trim());
             lst.SubItems.Add(rdr[2].ToString().Trim());
             lst.SubItems.Add(rdr[3].ToString().Trim());
             lst.SubItems.Add(rdr[4].ToString().Trim());
             frmSales.ListView1.Items.Add(lst);
         }
         frmSales.ListView1.Enabled = false;
         frmSales.Button7.Enabled = false;
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }
 }
 private void frmSalesRecord_FormClosing(object sender, FormClosingEventArgs e)
 {
     this.Hide();
     frmSales frm = new frmSales();
     frm.Show();
 }
 private void billingToolStripMenuItem_Click(object sender, EventArgs e)
 {
     frmSales frm = new frmSales();
     frm.Show();
 }