Question

I try to convert the following SQL Select statement in Linq2SQL:

SELECT stoptimes.stopid,
       trips.tripid,
       stoptimes.sequence
FROM   trips
       INNER JOIN stoptimes
               ON stoptimes.tripid = trips.tripid
WHERE  ( trips.routeid = '3' )
       AND ( trips.endplace = 'END001' )
ORDER  BY stoptimes.sequence DESC 

It works well but with linq2sql, I get an exception with this following statement:

var first = (from tableTrip in db.Trips
             join tableStopTimes in db.StopTimes on tableTrip.TripId equals tableStopTimes.TripId
             where tableTrip.RouteId == 3 && tableTrip.EndPlace == "TAEND"
             select new
             {
                 tableStopTimes.StopId,
                 tableStopTimes.Radius,
                 tableStopTimes.PlaceName,
                 tableStopTimes.Place,
                 tableStopTimes.Sequence
             }).OrderByDescending(X => X.Sequence).First();

Thanks

Answer 1

The error “Sequence contains no elements” is a result of the collection that you are calling First() on not having anything in it.

You can call FirstOrDefault instead to avoid this issue.

EDIT:

I believe in the case of the anonymous type that you are creating, the default will be null.