private void ComboxNam_Load(object sender, EventArgs e) { BUSGiaoVien a = new BUSGiaoVien(); DataTable dt = a.NamCombobox(); dt.Columns.Add("namhoc", typeof(string)); dt.Dispose(); cbxNamHocTTDK.ValueMember = "namhoc"; cbxNamHocTTDK.DataSource = dt; }