From: John Merlino <stoicism1@...>
Date: 2010-04-14T22:47:34+09:00
Subject: cumulative sum by month

Hey all,

While it is possible to doc cumulative sum by month in mysql using MONTH
and COUNT statements, I'm trying to figure out if the same kind of
statement is available in ruby, something like a substitute for the
month value I put below:

   def cumulative_sum
   values = [:passed_on, :failed_on, :incompleted_on]
   sum = 0
   case values
   when :passed_on
     month.each do |state|
     while state > '2010-03-00'
       @passed_on = state.map{ |x| sum += x}
     end
     end

     when :failed_on
        month.each do |state|
        while state > '2010-03-00'
          @failed_on = state.map{ |x| sum += x}
        end
        end

      when :incompleted_on
         month.each do |state|
         while state > '2010-03-00'
           @incompleted_on = state.map{ |x| sum += x}
         end
         end
         end
   end

Note that the passed_on, failed_on and incompleted_on fields of students
table are data typed as date.
Thanks for any response.
-- 
Posted via http://www.ruby-forum.com/.