具有多个内部连接的复杂SQL＆amp;用铁轨计数

Question

我想知道是否可以使用像这样的Rails Active Record帮助程序编写非常复杂的SQL（数字稍后会被变量替换）：

SELECT 
photographs.id,
(COUNT(distinct comments.id) / 50.0 * 100 * 0.25) + (15 * 0.1) + (COUNT(distinct likes.id) / 100.0 * 100 * 0.05) +(COUNT(distinct likes.id) / COUNT(distinct views.id) * 100 * 0.4) +(COUNT(distinct likes.id) * 2.4  / 100.0  * 0.2) AS FINAL_RANKING
FROM photographs
INNER JOIN comments 
ON photographs.id = comments.photograph_id
INNER JOIN likes 
ON photographs.id = likes.photograph_id
INNER JOIN views 
ON photographs.id = views.photograph_id
GROUP BY photographs.id
ORDER by FINAL_RANKING DESC;

我在Rails doc上找到了更简单的例子或简单的多内连接但没有计数

Answer 1

Rails在select命令中接受SQL。

请参阅Active Record Query Interface | Selecting Specific Fields

这样的事情对你有用：

Photographs.joins(:comments, :likes, :views, :users).where(
"users.id = 1").select("COUNT(whatever)")

无法保证实际运行。