Ordering nullable DateTime in Linq to SQL

问题:

I have started using Linq to SQL for a project im working on and i have run into a problem when ordering by a DateTime field but since the DateTime allows nulls the nulls are coming up as less than the actual dates in there.

So i pretty much want the ones with a date to be at the top (ordered either way) then all the ones with no date set.

jobList = from ju in context.Job_Users_Assigned
          where ju.UserID == user.ID
          select ju.Job;
return jobList.OrderByDescending(j => j.EndDate);

回答1:

This is a bit of a hack, but it appears to work with Linq to SQL:

return from ju in context.Job_Users_Assigned
          where ju.UserID == user.ID
          orderby ju.Created ?? DateTime.MaxValue descending;

So I'm substituting the maximum possible DateTime value when the actual "Create" value is null. That'll put all the null values at the top.

Another approach is to order by whether the date field has a value. This works too:

return from ju in context.Job_Users_Assigned
          where ju.UserID == user.ID
          orderby ju.Created.HasValue descending
          orderby ju.Created descending;