时间格式判断 datatable删除row

string sellerUserName = "fdfdfd";
        DateTime nowTime = DateTime.Now;
        dt = SpecialPriceCommodityDal.GetHasSelledSpecialPriceCommodity(sellerUserName);
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            DateTime time =Convert.ToDateTime(Convert.ToDateTime(dt.Rows[0]["publishTime"]).AddDays(Convert.ToInt32( dt.Rows["availableTime"])));
            if (time.CompareTo(nowTime) <= 0)
            {
                dt.Rows.RemoveAt(i);

            }
        }
            dlSpecialPriceCommodity.DataSource = dt;
        dlSpecialPriceCommodity.DataBind();