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: 20220309132719_copy_post_uploads_to_upload_references.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 CopyPostUploadsToUploadReferences < ActiveRecord::Migration[6.1]
  def up
    execute 
    
  def up
    execute <<~SQL
      INSERT INTO upload_references(upload_id, target_type, target_id, created_at, updated_at)
      SELECT post_uploads.upload_id, 'Post', post_uploads.post_id, uploads.created_at, uploads.updated_at
      FROM post_uploads
      JOIN uploads ON uploads.id = post_uploads.upload_id
      ON CONFLICT DO NOTHING
    SQL
  end