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";

}