LINQ语句中处理Datetime

1. AddDays

error：

Context.Article.Where(p => p.StartDate < DateTime.Now)
               .ToList()
               .Where(p => p.StartDate.AddDays(p.Period) > DateTime.Now);

fix：

Context.Article.Where(p => p.StartDate < DateTime.Now)
               .Where(p => EntityFunctions.AddDays(p.StartDate, p.Period)
                   > DateTime.Now);

2.是否是今天

else if (EndingBy == (int)EndingByEnum.Today)
                    {
                        var e4 = e.Where(x => (DateTime.Today.Year ==
                            ((DateTime)EntityFunctions.AddDays(x.StartBid, x.Duration)).Year &&
                            DateTime.Today.Month ==
                            ((DateTime)EntityFunctions.AddDays(x.StartBid, x.Duration)).Month &&
                            DateTime.Today.Day ==
                            ((DateTime)EntityFunctions.AddDays(x.StartBid, x.Duration)).Day));
                        return e4.ToList();
                    }

......