I read other posts on similar problem on using SingleOfDefault on Linq-To-Entity, some suggested using "First()" and some others suggested using "Extension" method to implement the Single().

This code throws exception:

Movie movie  = (from a in movies
                where a.MovieID == '12345'
                  select a).SingleOrDefault();

If I convert the object query to a List using .ToList(), "SingleOrDefault()" actually works perfectly without throwing any error.

My question is: Is it not good to convert to List? Is it going to be performance issue for more complicated queries? What does it get translated in SQL?

Movie  movie  = (from a in movies.ToList()
                where a.MovieID == '12345'
                  select a).SingleOrDefault();