Ruby on Rails

Now I figured out what is the error...
I dont know why... But rails changed the column name where you count froum comments_count to count_all... And you refer it on your order by statement using the alias you choose...
I hope somone more experienced on rails help you fix it, but for now... U could do 2 fix...

You can call the alias rails choose (count_all) on your order statement (ugly way to solve)
Or you can call for count(*) without alias on your order statement (more practiced by dba... Less ugly to solve)

Em 24/07/2013 07:40, "Yaw Boakye elGran" <yawboakye10@gmail.com> escreveu:

Error message:

      PG::Error: ERROR:  column "comments_count" does not exist  LINE 1: ...l, titles.created_at, titles.updated_at  ORDER BY comments_c...                                                               ^  : SELECT COUNT(*) AS count_all, titles.id, titles.title, titles.submitter_name, titles.submitter_email, titles.created_at, titles.updated_at AS titles_id_titles_title_titles_submitter_name_titles_submitter_e FROM "titles" INNER JOIN "comments" ON "comments"."title_id" = "titles"."id" GROUP BY titles.id, titles.title, titles.submitter_name, titles.submitter_email, titles.created_at, titles.updated_at  ORDER BY comments_count DESC

On Wed, Jul 24, 2013 at 10:38 AM, Yaw Boakye elGran <yawboakye10@gmail.com> wrote:

@Carlos this query still throws an exception:

def self.order_by_number_of_comments_descending
        select('titles.id, titles.title, titles.submitter_name, titles.submitter_email, titles.created_at, titles.updated_at, count(comments.id) AS comments_count').
        joins(:comments).
        group('titles.id, titles.title, titles.submitter_name, titles.submitter_email, titles.created_at, titles.updated_at').
        order('comments_count DESC')
    end

still complaining about not finding comments_count :/

I'm using PostgreSQL 9.1.5

On Wed, Jul 24, 2013 at 10:32 AM, Yaw Boakye elGran <yawboakye10@gmail.com> wrote:

I think so, sorry for the misinformation. Thanks for the correction :)

On Wed, Jul 24, 2013 at 12:36 AM, Scott Ribe <scott_ribe@elevated-dev.com> wrote:

On Jul 23, 2013, at 6:28 PM, Yaw Boakye elGran <yawboakye10@gmail.com> wrote:

>       • During grouping, the normal SQL requirement is to group on a column that is on both tables. As far as I know, grouping can't be done on two tables when they don't a common column. In your group call, only titles.id would be useful. The rest won't

You seem to be confusing the grouping with the join condition. The join requires 1 (usually, sometimes more) column common to both tables. The grouping must include all columns not used in the aggregate function.


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