sql - 将 SQL 查询转换为 ActiveRecord 查询

Question

问题:我不知道如何转换这个 PostgreSQL 查询:

select news_id, sum(case when likes.like then 1 else -1 end) as max_positive from likes group by(news_id) order by(max_positive) desc

到 ActiveRecord 查询。

我尝试过的:

Like.group(:news_id)
    .sum('CASE WHEN likes.like THEN 1 ELSE -1 end')
    .max_by { |_k, v| v }

但结果是数组而不是选择 news_id。

Answer 1

像这样？

Like.group(:news_id).select("news_id, SUM(case when likes.like then 1 else -1 end) as max_positive").order("max_positive desc")