ActiveRecord, Rails ORM was the poster child of ORMs for a while, and is completely abysmal for non-trivial left joins, non-trivial aggregations and some subque

ActiveRecord, Rails ORM was the poster child of ORMs for a while, and is completely abysmal for non-trivial left joins, non-trivial aggregations and some subqueries. Of course using raw SQL is possible but might force you into converting other parts of the code into raw SQL. There is Arel, but it's just a more verbose SQL in quasi-AST form. On the other hand, I never had much problems with LINQ or Hibernate.