[Rails] (Newb alert) One-to-many...

Have you read these?

   http://guides.rubyonrails.org/association_basics.html
   http://guides.rubyonrails.org/migrations.html

In general you should make changes to your DB through migrations
only, so you can reverse, repeat, insure identical changes are made
to other (deployment) systems, etc.

Work right through a good tutorial such as railstutorial.org (free to
use online) and all the basics (including associations) will become
clear.

Colin

Example: an owner has many cats.

In your Cat model, add the line:
belongs_to :owner

in your Owner model, add the line:
has_many :cats

You then need to run a migration on your cats table, to add the foreign key
for owners, so Rails can build the associations. From the command line:

rails g migration add_owner_id_to_cats owner_id:integer

This should create a migration file (in the /db folder), with something
like the following in it:

class AddFooToPosts < ActiveRecord::Migration
   def change
     add_column :cats, :owner_id, :integer # ie, table, field name, field
type
   end
end

then, run your migration.

rake db:migrate

Thanks to the convention over configuration approach, rails will
automagically work out that owner_id is a foreign key to the owners table.
from there, you'll be able to access cats through owners, and owners
through cats:

mog.owner # "Steve"
steve.cats.first # "Mog"

That, of course, is just the tip of the iceberg - you can define all kinds
of odd relations, and customise them as much as you want.

JT

NB: AddFooToPosts would be AddOwnerIdToCats, I just messed up the copy
paste.