User195

class CreateRelationships < ActiveRecord::Migration
  def change
    create_table :relationships do |t|
      t.integer :follower_id
      t.integer :followed_id

      t.timestamps
    end

    add_index :relationships, :follower_id

User195

class Relationship < ActiveRecord::Base
  attr_accessible :followed_id

  belongs_to :follower, class_name: "User"
  belongs_to :followed, class_name: "User"

  validates :follower_id, presence: true
  validates :followed_id, presence: true

User195

class User < ActiveRecord::Base
 
  .
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  .

User195

C:\Sites\rails_project\sample_app>bundle exec rake db:reset
Couldn't drop db/development.sqlite3 : #<Errno::EACCES: Permission denied - C:/Sites/rails_project/sample_app/db/development.sqlite3>
db/development.sqlite3 already exists
-- create_table("microposts", {:force=>true})
   -> 0.0400s
-- add_index("microposts", ["user_id", "created_at"], {:name=>"index_microposts_on_user_id_and_created_at"})
   -> 0.0070s
-- create_table("relationships", {:force=>true})
   -> 0.0220s
-- add_index("relationships", ["followed_id"], {:name=>"index_relationships_on_followed_id"})