DataGrid编辑项中提取出FileUpload的值

朋友们如何提取DataGrid模版列里面的FileUpload的值呢? 哪位好心的朋友可以帮我把代码完善一下..我是需要把FileUpload里的路径提取出来然后写到数据库里
 protected void DataGrid1_UpdateCommand(object source, DataGridCommandEventArgs e)
        {
            //编辑中更新按钮
                       string cpid = this.DataGrid1.DataKeys[e.Item.ItemIndex].ToString(); //首先获取表中主键
            string cptype = ((TextBox)(e.Item.Cells[1].Controls[0])).Text;
            
            FileUpload cpimg = ((FileUpload)(e.Item.Cells[2].Controls[0]));
            
            string cpxinxi= ((TextBox)(e.Item.Cells[3].Controls[0])).Text;
            
            SqlConnection con = DBCon.GetCon();
            SqlCommand cmd = new SqlCommand("update chanpian set ChanpinName='" + cptype + "',ChanpinImg='" + cpimg + "',ChanpinXinxi='" + cpxinxi + "' where ChanpinID='" + cpid + "'", con);
            con.Open();
            cmd.ExecuteNonQuery();
            this.DataGrid1.EditItemIndex = -1;
            this.DataGridToBind();
        }