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: 20211123033311_reset_first_unread_pm_at_on_user_stat.rb
    path of file: ./repos/discourse/db/migrate
    
    the code of the file until where you have to start completion: # frozen_
    
  def up
    execute <<~SQL
    UPDATE user_stats us
    SET first_unread_pm_at = u.created_at
    FROM users u
    WHERE u.id = us.user_id
    SQL
  end