Lambda 表达式月份的开始日期和月份的结束日期

Question

 startDate = DateTime.Now;
            endDate = DateTime.Now;
            ResponseDeliveryOrderCountDetails monthDeliveryOrderEarning = (from deliveryBoys in db.tblDeliveryBoys
                                                                           where deliveryBoys.Mobile == mobile
                                                                           select new ResponseDeliveryOrderCountDetails()
                                                                           {
                                                                               // OrdersCount = (from earnings in db.tblDeliveryEarnings.Where(x => x.DeId == deliveryBoys.DeId && x.DeliveryStatus == 1 && x.DeliveryStatus == 1 && DbFunctions.TruncateTime(x.DeliveryDate) >= DbFunctions.TruncateTime(startDate) && DbFunctions.TruncateTime(x.DeliveryDate) <= DbFunctions.TruncateTime(endDate)).GroupBy(y => DbFunctions.TruncateTime(y.DeliveryDate))
                                                                               //select earnings.ToList().Count).ToList(),
                                                                               OrderCount = (from earnings in db.tblDeliveryEarnings.Where(x => x.DeId == deliveryBoys.DeId && x.DeliveryStatus == 1 && DbFunctions.TruncateTime(x.DeliveryDate) >= DbFunctions.TruncateTime(startDate) && DbFunctions.TruncateTime(x.DeliveryDate) <= DbFunctions.TruncateTime(endDate)).GroupBy(y => DbFunctions.TruncateTime(y.DeliveryDate))
                                                                                             select earnings.ToList().Count).ToList().Sum(),
                                                                               Earnings = db.tblDeliveryEarnings.Where(x => x.DeId == deliveryBoys.DeId && x.DeliveryStatus == 1 && DbFunctions.TruncateTime(x.DeliveryDate) >= DbFunctions.TruncateTime(startDate) && DbFunctions.TruncateTime(x.DeliveryDate) <= DbFunctions.TruncateTime(endDate)).ToList().Select(x => x.Earnings.Value).Sum(),
                                                                               WorkingHours = db.tblDeliveryAttenances.Where(x => x.DeId == deliveryBoys.DeId && DbFunctions.TruncateTime(x.SlotDate) >= DbFunctions.TruncateTime(startDate) && DbFunctions.TruncateTime(x.SlotDate) <= DbFunctions.TruncateTime(endDate)).ToList().Select(x => x.WorkingHours.Value).Sum(),
                                                                               DeliverEarnEnum = DeliveryEarningEnum.CurrentMonth.ToString()

                                                                           }).FirstOrDefault();



            responseDeliveryOrderCountDetails.Add(monthDeliveryOrderEarning);

我有一个 Lambda 表达式，我需要计算当月开始日期和当月结束日期的数据。

有什么办法可以设置开始日期和结束日期吗？