DataSet重新生成DataTable再绑定DataGrid

System.Data.DataSet ds = da.getDataSet(strDL,strDW);
DataTable tbl = ds.Tables.Add("aa");
tbl.Columns.Add("DM",typeof(string));
tbl.Columns.Add("SQBH",typeof(string));
int m = ds.Tables[0].Rows.Count;
for(int k=0;k<m;k++)
    {
        string strDM = ds.Tables[0].Rows[k]["DM"].ToString();
        if(strDM != ""&&strDM != null)
        {
            DataRow row = ds.Tables["WG_SQDM"].NewRow();
            row["DM"] = strDM;
            row["SQBH"] = ds.Tables[0].Rows[k]["SQBH"].ToString();
            ds.Tables["aa"].Rows.Add(row);
        }
    }
dg.DataSource=ds.Tables["aa"];
dg.DataBind();