Linq to Sql Sum with no records

Question

I am creating a method that collects accumulated totals throughout the month. The problem is that there may not be charges for some of the items in a given month so no rows would be returned.

I can see how this would error with no data:

double fuelCost = (double)(from a in db.EquipmentFuelLogs
                           where a.wdEquipmentMainGeneralOID == vehicleKey &&    
                                (monthBeginDate < a.Date1 && a.Date1 < monthEndDate)
                           select a.TotalCost).Sum();

What is the best approach to detect no fuel transactions for that month and set the fuel cost to 0? Just do a try catch? This article spoke of the problem but no solution.

Answer 1

monthBeginDate >= a.Date1

Answer 2

Why would it error with no data?

It is zero then, that's how it works (well unless I am completely mistaken here).

Answer 3

I added a catch to catch the error. I never found a different solution.

Answer 4

The issue is because the where is returning no sequence therefor the sum cannot work, however if you use .DefaultIfEmpty before the sum it works fine.

decimal? orderValue = orders.Where(ee => ee.Name == "SomeName") .DefaultIfEmpty().Sum(s => s.OrderCost);

Hope this helps.