GROUP BY +多列轨道3总和 [英] group by + sum on multiple columns in rails 3

问题描述

我需要得到订购的照片的数量，我在数据库，这些位置的位置列表，这里是我的查询

I need to get a list of locations ordered by the number of picture that I have in the DB for these locations, here is my query

Location.select(:city).group(:city).order("SUM(images_count) DESC").sum(:images_count)

这工作就像一个魅力，不幸的是，我现在需要添加全省乃至全国prevent含糊不清的出现，所以我现在有这个

This worked like a charm, unfortunately, I now need to add province and country to prevent ambiguities to arise, so I now have this

Location.select(:city, :province, :country).group(:city, :province, :country).order("SUM(images_count) DESC").sum(:images_count)

这是不工作：（

And this is not working :(

有人能帮助我这个查询？

Could someone help me out with this query?

推荐答案

我还不是很骄傲我的解决方案，但它的工作原理：

I'm not very proud of my solution but it works:

Location.group(:city, :province, :country)
        .select(:city, :province, :country, "SUM(images_girl_count) as sum_images_count")
        .order("sum_images_count DESC")
        .collect{ |location| [location.city, location.province, location.country, location.sum_images_count] }

任何意见？

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