# Rails: Update Comments Count for All Topics in a Group

```ruby
def update_topics_comments_count
  begin
    ActiveRecord::Base.connection.execute <<~SQL
      UPDATE topics
         SET comments_count = (SELECT count(1)
                                 FROM topic_comments
                                WHERE topic_comments.topic_id = topics.id
                                  AND topics.group_id = '#{group.id}')
    SQL
  ensure
    ActiveRecord::Base.connection.close
  end
end
```