Question

I am trying to learn MVC and nHibernate by creating a simple blog application.

I have a posts table and a comments table. Each post can have multiple comments. Now in my view I have to display the details of the post and the number of comments.

I tried the below code

(from post in DbContext.Posts
where post.ScheduledDate <= DateTime.Now && post.Approved == true
orderby post.ScheduledDate descending
select new { Post = post, CommentCount = post.Comments.Count() }).Take(10);

This returns the below SQL:

SELECT top 10 count(comments1_.Id) as y0_ 
FROM Posts this_ 
left outer join Comments comments1_ 
         on this_.Id=comments1_.PostId 
WHERE (this_.ScheduledDate <= '2009-12-29' and this_.Approved = 1) 
ORDER BY this_.ScheduledDate desc

And obviously throws a sql exception that group by is not used.

Answer 1

Looks like this was some weird issue with the NHContrib LINQ provider. I upgrade to version 3 of nHibernate and the new LINQ provider seems to be working perfectly well for the same query.