private void cmbTimTheo_SelectedIndexChanged(object sender, EventArgs e)
{
AutoCompleteStringCollection auto = new AutoCompleteStringCollection();
DataTable dt = new DataTable();
dt = HoaDon_BLL.LayMaHoaDon();
foreach (DataRow dr in dt.Rows)
{
if (cmbTimTheo.SelectedIndex == 0)
{
auto.Add(dr[0].ToString());
}
}
txtTuKhoa.AutoCompleteSource = AutoCompleteSource.CustomSource;
txtTuKhoa.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
txtTuKhoa.AutoCompleteCustomSource = auto;
}