private void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
if (ddlState.SelectedValue.ToString() != null)
{
int stateId = Convert.ToInt32(ddlState.SelectedValue);
CompanyBL companyBL = new CompanyBL();
List <City> cities = companyBL.GetCities(stateId);
ddlCity.ValueMember = "ID";
ddlCity.DisplayMember = "Name";
ddlCity.DataSource = cities;
}
}