Adding times in ruby on rails

I currently have a model called Job which has an attribute called CPU. This corresponds to the CPU time that a job was running. I would like to add all the time attributes of all the jobs for a specific date. This column is in the time format 00:00:00. Therefore I thought this would work:

def self.cpu_time
  sum(:cpu)
end

Which returns the following "Sat Jan 01 00:00:00 UTC 2000".

For my test data, I used the following cpu times: 00:00:46 00:26:46

Any he开发者_运维问答lp would be appreciated

This solved my problem, although it doesnt seem to be the rails way:

def self.cput
    @times = find(:all,
                :select => 'cput')
   @total_time =0
    for time in @times do  
      @total_time += time.cput.to_i - 946684800
      end
   @total_time  

  end

You don't state what data type you're using for the cpu column. Personally I would store it in seconds and then convert to hours, minutes and seconds after summing it.