combox 绑定数据后增加item

 //给楼道好下拉框初始化

        private void InitCmb_dh()

        {

            AccessDbHelper.ConnectionString = ConfigurationManager.ConnectionStrings["acc"].ConnectionString;  //连接字符

            string sql = "select  楼栋代码,楼栋名称 from 楼栋表 where 管理单位='" + globeInfo.g_OfficeCode + "' ";

           

            DataSet ds2 = AccessDbHelper.Query(sql);

            DataTable dt = new DataTable();

            dt = ds2.Tables[0];

            DataRow dr = dt.NewRow();

            dr[0] = "0";

            dr[1] = "所有楼栋";

            dt.Rows.InsertAt(dr, 0);

            cmb_system.DataSource = dt;

            cmb_system.DisplayMember = "楼栋名称";

            cmb_system.ValueMember = "楼栋代码";

        }