将已查询的Datable动态添加列 和行的问题
求高手指教
为什么我添加不上去 列能上去 但是行不显示

   DataTable dt = (DataTable)ZouXiuERP.Common.BLL.OracleHelper.ExecuteDataTable(ConfigurationManager.ConnectionStrings["ebs_Conn"].ToString(), sql);



        DataColumn dc1 = new DataColumn("category", Type.GetType("System.String"));

        DataColumn dc2 = new DataColumn("materials", Type.GetType("System.String"));

        

        dt.Columns.Add(dc1);

        dt.Columns.Add(dc2);



        if (dt.Rows.Count > 0)

        {



          

        

            for (int i = 0; i < dt.Rows.Count; i++)

            {

               

                 DataRow dr = dt.NewRow();

                dr["category"] = "test";

                dr["materials"] = "test2";

                dt.Rows.Add(dr);

          

            }



        

            

        }

------解决方案--------------------
for (int i = 0; i < dt.Rows.Count; i++)
            {
               
                 DataRow dr = dt.Rows[i];
                dr["category"] = "test";
             &nbs