asp.net dataTable添加列

  DataTable dtNew = new DataTable();
        dtNew.Columns.Add("ItemNo");//序列号列
        dtNew.Columns.Add("flowname");
        dtNew.Columns.Add("flowcontent");
        dtNew.Columns.Add("bussinessflowid");
        int p = 1;
        for (int i = 0; i < dtOld.Rows.Count; i++)
        {
            DataRow dr = dtNew.NewRow();
            dr["ItemNo"] = (p++).ToString();
            dr["flowname"] = dtOld.Rows[i]["flowname"].ToString();
            dr["flowcontent"] = dtOld.Rows[i]["flowcontent"].ToString();
            dr["bussinessflowid"] = dtOld.Rows[i]["bussinessflowid"].ToString();
            dtNew.Rows.Add(dr);
        }

        datalist.DataSource = dtNew;
        datalist.DataBind();