在 Rails 中分组、计数、拥有和排序

本文介绍了在 Rails 中分组、计数、拥有和排序的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个表:people，其中有一列名为:age.

I have a table: people with a column named: age.

如何计算每个年龄的人数，从大到小排序，按年龄过滤，其中至少有 2 个人?

How can I get a count of the people with each age, ordered from oldest to youngest, filtered by ages with at least 2 people in it?

我将如何用原始 SQL 编写它:

SELECT COUNT(1) AS people_count, age FROM people GROUP BY age HAVING people_count > 1 ORDER BY age DESC

在 Rails 中(我不知道怎么做):

Person.group(:age).count 将按 age 获取计数，但我不知道如何按年龄降序排列，或者添加have 子句.

Person.group(:age).count will get me the counts by age, but I can't figure out how to order it descendingly by age, or add the having clause.

推荐答案

尝试类似:

Person.select("id, age").group(:id, :age).having("count(id) > 1").order("age desc")