通過sql按周統計詳見https://www.cnblogs.com/ZhengHengWU/p/13305104.html

           //資料庫通過sql查出按周分組的統計資料
            List<Statistics> dbList = new List<Statistics>();

            //獲取近十週的日期列表
            DateTime dt = DateTime.Now;
            DateTime startWeek1 = dt.AddDays(1 - Convert.ToInt32(dt.DayOfWeek.ToString("
 
d")));  //本週週一
            var newDt = startWeek1.AddDays(-(9 * 7));
            List<Statistics> list = new List<Statistics>();
            list.Add(new Statistics { CreateDate = newDt.ToString("yyyy-MM-dd") });
            for (int i = 1; i < 9; i++)
            {
                newDt 
 
= newDt.AddDays(7);
                list.Add(new Statistics { CreateDate = newDt.ToString("yyyy-MM-dd") });
            }
            list.Add(new Statistics { CreateDate = startWeek1.ToString("yyyy-MM-dd") });

            //通過遍歷近十週的日期進行和資料庫查出來的資料進行比較，本週有值取count,沒值本週預設count為0
            foreach (var item in
 
 list)
            {
                item.Count = dbList.Where(t => t.CreateDate == item.CreateDate)?.FirstOrDefault()?.Count ?? 0;
            }

實體類：

public class Statistics
    {
        public string CreateDate { get; set; }
        public int Count { get; set; } = 0;
    }