.net 时间的比较

 string dbpath = Server.MapPath("db/count.mdb");
            DbAccess db = new DbAccess(dbpath);
            #region "添加"
            string url = Convert.ToString(Request.UrlReferrer);
            string ip  = Convert.ToString(Request.UserHostAddress);

            //判断
            string sqlsel = string.Format("select count(*) from record where ip='{0}'",ip);
            int coun = Convert.ToInt32(db.GetDataTable(sqlsel).Rows[0][0].ToString());
            bool add=false;
            if(coun>0)
            {
                    sqlsel  = string.Format("select [date] from record where ip='{0}'order by date desc",ip);
                    DateTime dt = Convert.ToDateTime(db.GetDataTable(sqlsel).Rows[0]["date"].ToString());
                    DateTime now = DateTime.Now;
                    TimeSpan ts = now-dt;
                    double time = ts.TotalHours;
                if(time>2)
                {
                    add=true;
                }
                else
                {

                }
                    
            }
            else
            {
                add=true;
            }
            //添加
            if(add)
            {
        string sqladd = string.Format("insert into record(url,ip) values('{0}','{1}')",url,ip);
           
            db.ReturnState(sqladd);
            }
    
#endregion
            #region 显示
    
            DataSet ds = new DataSet(); 
                ds=db.GetDataSet("select count(*) from record");
            
            this.coun=Convert.ToString(ds.Tables[0].Rows[0][0]);
            #endregion

    DateTime now = DateTime.Now;
            DateTime ot  = DateTime.Now.AddDays(3);
            long  al = now.Ticks;
            long  ot1 = ot.Ticks;
            Response.Write(al);
            Response.Write("<br>");
            Response.Write(ot1);
            Response.Write("<br>");
            Response.Write(ot1-al);
            Response.Write("<br>");

            Response.Write(((ot1-al)/10000/1000)/(60*60*24));//相差几天