mysql – 如何在Rails3中的Active Record中按天和年分组

我正在尝试在rails 3中重新创建以下mysql查询

 select count(id),year(created_at),month(created_at) from table where published_state = 'published' group by year(created_at),month(created_at);

我尝试过类似的东西：

results = Table.select('count(id),month(created_at)').where('published_state LIKE ?','published').group('year(created_at),month(created_at)')

但它不会返回我想要的东西.

我只是得到了回报

[#

Table.where(:published_state => 'published').
  group('year(created_at)').group('month(created_at)').count(:id)