[Rails] Re: active record question

You could either use the find_by_sql method or the :joins method. (As
someone has stated earlier that avoid find_by_sql for performance and
maintanence reasons)

sample sql to put in find_by_sql in your model

select question_id from responses r1
where not exists
(select question_id from question q )

using :joins. (probably this would be better )

questions.find( :joins => "LEFT OUTER JOIN responses ON question_id =
responses.question_id" :conditions => "responses.id is null")

gurus, please comment on this.

thanks,
radha.

badnaam wrote:
> I have three models, Question, Response and User
>
> User has many question, :through Responses
>
> My response table has 3 main columns response, question_id and
> user_id.
>
> The use case is lets say the user can respond to 100 question, but
> during a session he responds to 20. How do I find out the ones he has
> not respondeded to. In this case the response table will have 20
> records and I woukd like to show the user the rest of the 80 he has
> not responded to.
>
> Thanks

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