DataTable（ComboBox）第一项添加空值

          DataTable dt = new DataTable(); 
            dt = typebll.getDateByType(PublicEnum.DefinedType.节点类型.ToString());

            DataRow r = dt.NewRow();
            r["TypeName"] = "";
            r["ID"] = "";
            dt.Rows.InsertAt(r,0);
          
            this.cbTypeName.DataSource = dt;
            this.cbTypeName.DisplayMember = "TypeName";
            this.cbTypeName.ValueMember = "ID";

注意是Rows.InsertAt方法