复杂的铁路查询 - 工会？子选择？我还可以使用named_scope吗？

Part of why I love Rails is that I hate SQL - I think it's more like an assembly language that should be manipulated with higher level tools such as ActiveRecord. I seem to have hit the limits of this approach, however, and I'm out of my depth with the SQL.Part of why I love Rails is that I hate SQL - I