Sum enumeration with LIMIT


#1

Hi everyone.

I’m trying to SUM the places of the first 5 finishers in a Cross
Country running event. In a Cross Country race the team score is
based upon the sum of the top 5 runners on your team. The lowest team
score at the competition wins.

I have EVENTS(the race), PARTICIPANTS(the runner), and
EVENT_PARTICIPANTS(a runner in a race).

Within event_participant I have this code, which doesn’t work as it
adds places beyond the 5th runner.

def self.score_5
self.calculate(:sum, :finish_place, :order
=> :finish_place, :limit => 5)
end

It appears that the LIMIT is ignored or is applied after the
summation.

Any suggestions?


#2

On 7 Dec 2008, at 19:37, yajiri wrote:

It’s applied after (so if you did select sum(foo) from bars limit 5
then you’d only get 5 rows back).
Something like
SELECT sum(finish_place) from
(SELECT * from some_table order by finish_place limit 5) as sub_select

should do it.

Fred


#3

Are us suggesting find_by_sql?

On Dec 7, 1:48 pm, Frederick C. removed_email_address@domain.invalid


#4

I’d like to know if there is a way to use ActiveRecord to do this.

Thx