class AddSelfEditsToPosts < ActiveRecord::Migration[4.2] def up add_column :posts, :self_edits, :integer, null: false, default: 0 execute " UPDATE posts p SET self_edits = (SELECT COUNT(*) FROM post_revisions pr WHERE pr.post_id = p.id AND pr.user_id=p.user_id) " end def down remove_column :posts, :self_edits end end