谢谢大家  问题解决了 现在把答案  公布            SqlCommand myCmd = new SqlCommand("Select * from cp" ,FangFa.myCn);
            SqlDataReader mySdl;
            mySdl=myCmd.ExecuteReader();
           
            cpbhtxt.Items.Clear();
            while (mySdl.Read())
            {
                cpbhtxt.Items.Add(mySdl.GetValue(0));
            }