LINQ中判断日期时间段

1）、定义

DateTime dtToday = Convert.ToDateTime(DateTime.Now.ToString("yyyy-MM-dd"));//今天 DateTime dtNexDay = Convert.ToDateTime(DateTime.Now.AddDays(1).ToString("yyyy-MM-dd"));//明天 DateTime dtWeekDay = Convert.ToDateTime(DateTime.Now.AddDays(7).ToString("yyyy-MM-dd"));//一周 DateTime dtMonthFirstday = Convert.ToDateTime(new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1).ToString("yyyy-MM-dd"));//本月 DateTime dtThreeMonth = Convert.ToDateTime(new DateTime(DateTime.Now.Year, DateTime.Now.AddMonths(-3).Month, 1).ToString("yyyy-MM-dd"));//3个月 DateTime dtYearFirstday = Convert.ToDateTime(new DateTime(DateTime.Now.Year, 1, 1).ToString("yyyy-MM-dd"));//今年

2）、LINQ

var query = db.Query<Teacher>().Where(c=>c.Date>dtToday&&c.Date<dtNexDay)