ActiveRecord Associations Question

I'm new to rails and have volunteered to help out the local High School Track team with a simple database that tracks the runners performances. For the moment, I have three models: Runners, Race_Data and Races. I have the following associations.

Runners have_many Race_Data
Races have_many Race_Data

I also want create the association Runners Have_Many Races Through Race_Data, but as my look at the diagram I have drawn, there is already a many to one relationship from Race_data to Races. Does the combination of Runners having many Race_Data and Race_Data having one Race imply a Many_to_Many relationship between Runners and Races?

From stackoverflow

• The relationship you describe is implied, but using it involves more complex code than might be needed. I think you want something more like

  class Runner < ActiveRecord::Base
    has_many :entries
    has_many :races, :through => :entries
  end
  class Race <  ActiveRecord::Base
    has_many :entries
    has_many :runners, :through => :entries
  end
  class Entry < ActiveRecord::Base
  # I suggest this is a more expressive name than "Race_Data"
    belongs_to :runner
    belongs_to :race
  end
  

  That should be enough to do stuff like this:

  bob = Runner.new(:name=>'Bob')
  joe = Runner.new(:name=>'Joe')
  race = Race.new(:race_date=>'20100313')
  race.entries.create(:runner=>joe, :position=>1)
  race.entries.create(:runner=>bob, :position=>2)
  bob.races.all #=> [#<Race id: 1, race_date: "2010-03-13"]
  bob.entries.all #=> => [#<Entry id: 2, runner_id: 1, race_id: 1, position: 2]
  

  Mutuelinvestor : Mike, Thanks for your great response. Also great suggestion on using Entries instead of race_data. Jim