You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20200617144300_add_public_field_to_published_pages.rb
    path of file: ./repos/discourse/db/migrate
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class AddPublicFieldToPublishedPages < ActiveRecord::Migration[6.0]
  def up
    # Delete the record of https://github.com/discourse/discourse/commit/b9762afc106ee9b18d1ac33ca3cac281083e4
    
  def up
    # Delete the record of https://github.com/discourse/discourse/commit/b9762afc106ee9b18d1ac33ca3cac281083e428e
    execute <<~SQL
      DELETE FROM schema_migrations WHERE version='20201006172700'
    SQL

    # Delete the reference to the incorrectly versioned version of this migration
    execute <<~SQL
      DELETE FROM schema_migrations WHERE version='20201006172701'
    SQL

    # Using IF NOT EXISTS because the version number of this migration was changed
    # Therefore some sites may have already added the column
    execute <<~SQL
      ALTER TABLE "published_pages" ADD COLUMN IF NOT EXISTS "public" boolean DEFAULT FALSE NOT NULL
    SQL
  end