class DeleteCategories < ActiveRecord::Migration def self.up remove_column :projects, :category_id drop_table :categories end def self.down create_table :categories, force: true do |t| t.string "name" t.string "ancestry" t.integer "projects_count", default: 0, null: false t.datetime "created_at" t.datetime "updated_at" end add_column :projects, :category_id, :integer end end