datagrid 一列的和

   DataSet ds = new DataSet();
   da.Fill(ds,"studentinfo");
   dgShow.DataSource = ds.Tables["studentinfo"].DefaultView;
   dgShow.DataBind();
   //以下作分数和的统计
   int count=0;
   for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
   {
    count += int.Parse(ds.Tables[0].Rows[i]["Score"].ToString());
   }
   int nAv = count/ds.Tables[0].Rows.Count;
   foreach(DataGridItem dgi in dgShow.Controls[0].Controls)
   {
    if (dgi.ItemType == ListItemType.Footer)
     dgi.Cells[6].Text = "平均："+nAv.ToString();
   }