LINQ查询获取最近30天的记录

Question

I have a LINQ query to find records for the last 7 days which works fine. Although if I try use the same query but for the last 30 days then 0 is returned. Can anyone tell me why this is? And how can I edit the query to work for the last 30 days?

Works fine:

//calories burned working out over the last 7 days
        public int CaloriesBurnedLast7Days
        {
            get
            {
                using (var db = new FitnessTrackerWebAPIContext())
                {
                    int calsLast7Days = 0;
                    calsLast7Days = db.Workouts.Where(w => w.Date <= DateTime.Now.AddDays(-7) && w.UserID == ID).Sum(w => w.CaloriesBurned);
                    return calsLast7Days;
                }
            }
        }

Does not work correctly:

//calories burned working out over the last 30 days
        public int CaloriesBurnedLast30Days
        {
            get
            {
                using (var db = new FitnessTrackerWebAPIContext())
                {
                    int calsLast30Days = 0;
                    calsLast30Days = db.Workouts.Where(w => w.Date <= DateTime.Now.AddDays(-30) && w.UserID == ID).Sum(w => w.CaloriesBurned);
                    return calsLast30Days;
                }
            }
        }

Answer 1

I have a LINQ query to find records for the last 7 days which works fine

No, you have a query that returns the calories burned more than 7 days ago (ie 8, 9, 10, etc). The way you structured your query, the correct way would be w.Date >= DateTime.Now.AddDays(-n) to get the last n days.