ar_migration_snippet1.rb

class CreateArtists < ActiveRecord::Migration
  def change
    create_table :artists do |t|
      t.string :name

      t.timestamps
    end

    add_index :artists, :name
  end
end

class CreateSongs < ActiveRecord::Migration
  def change
    create_table :songs do |t|
      t.string :title
      t.integer :artist_id

      t.timestamps
    end

    add_index :songs, :title
    add_foreign_key :songs, :artists
  end
end