migrationの記述の仕方が変わってる(sexy migration) † こんな感じ 20080727003719_create_categories.rb create_table :categories do |t| t.string :name t.string :image_url t.text :description t.timestamps end 20080727003748_create_products.rb create_table :products do |t| t.references :category t.string :name t.string :image_url t.text :description t.timestamps end 参考) http://api.rubyonrails.org/classes/ActiveRecord/Mig