private void btnDelete_Click(object sender, EventArgs e)
 {
     if (detail.SalesID == 0)
     {
         MessageBox.Show("Please select a sales from table");
     }
     else
     {
         DialogResult result = MessageBox.Show("Are you sure?", "Warning!!", MessageBoxButtons.YesNo);
         if (result == DialogResult.Yes)
         {
             if (bll.Delete(detail))
             {
                 MessageBox.Show("Sales was deleted");
                 bll = new SalesBLL();
                 dto = bll.Select();
                 dataGridView1.DataSource = dto.Sales;
                 CleanFilters();
             }
         }
     }
 }