Setting output parameter inside LINQ select
No, you can't do that, you can't use out parameters in a lambda.

But even if you could, I don't think it would be a good idea to do so, because it would make the code less readable.

There are also some suspicious practices in your code:


You're using SingleOrDefault(), but you don't check the result for null. If you don't want to check for null, use Single() which will throw an exception if the query returns an empty collection.
You're catching all exceptions. You should catch only the exceptions you know about. And you certainly shouldn't use something like return -1, it's much better to just let the exception bubble up and catch it somewhere up the call stack. Another option might be catching the exception, wrapping it in some more specific exception and throwing that.
Why are you setting the output parameters to 0 by default? They are nullable, so setting them to null makes more sense to me.