Harold to me As far as I know, the reason for :include is mainly for eager loading. If you know you will be querying the sections table for the companies you are finding, doing an :include will retrieve those sections in one query, ie, one trip to the DB. If you don't pass in the :include option to the initial find, doing the_company.all-sections would go to the database to retrieve the associated records and then build the section object.
I usually use :joins when I want to narrow down the search even further, for instance, to companies who have sections, persons who also have users, etc. For example: Company.find(:all, :include => :all-sections, :conditions => '...') Would fetch all companies meeting those conditions, along with the associated "all-section"s. Therefore it doesn't make sense to force it to :select any specific columns, especially not columns on only one of the tables - it defeats the purpose of the :include. On the other hand: Company.find(:all, :joins => :all-sections, :conditions => '..', :select => 'company.*') works fine, however, :select => 'company.*' is redundant, and if you will need the returned companies' sections, you will make a trip to the DB that may have been avoided by using :include. On Nov 18, 6:41 pm, boblu <[EMAIL PROTECTED]> wrote: > yes, the compannies table does not have a columns called > ref_company_id. > It is the table which is referreced by the sections table that has a > ref_company_id as a foreign key. > Can you explain why that error comes out? 'cause I cannot find any > clue about it. > > And thank you for mentioning your blog post, and I now know why I feel > my app is much faster using join than using include. > Thank you. > > On Nov 18, 7:37 pm, Frederick Cheung <[EMAIL PROTECTED]> > wrote: > > > Well to answer the question in the subject line, I wrote this a little > > while > > back:http://www.spacevatican.org/2008/6/22/the-difference-between-include-... > > A key thing to note is that include in 2.1 and include in 2.0.2 are > > different (but the 2.1 code will fall back to the 2.0.2 code if > > necessary). > > Does the companies table not have columns called ref_company_id ? > > > Fred --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
