protected void reportShowButton_Click(object sender, EventArgs e)
{
DateTime lowerDate = DateTime.Parse(lowerDateTextBox.Value.ToString());
DateTime upperDate = DateTime.Parse(upperDateTextBox.Value.ToString());
BillManager billManager = new BillManager();
List <ViewUnpaidBill> viewUnpaidBillList = billManager.GetUnpaidBillsByDate(lowerDate, upperDate);
billShowGridView.DataSource = viewUnpaidBillList;
billShowGridView.DataBind();
double totalAmount = 0;
foreach (ViewUnpaidBill viewUnpaidBill in viewUnpaidBillList)
{
totalAmount += viewUnpaidBill.BillAmount;
}
totalAmountTextBox.Value = totalAmount.ToString();
}
