Ruby on rails Ruby Postgresl组语句

我有以下postgresql语句，它在navicat for postgresql中运行正常

SELECT date_trunc('day', updated_at), count(*) as total_count 
FROM "persons"
WHERE ("persons"."updated_at" BETWEEN '2012-10-17 00:00:00.000000' AND '2012-11-07   12:25:04.082224') 
GROUP BY date_trunc('day',updated_at)
ORDER BY count(updated_at) DESC

我得到了预期的结果，比如

2012-10-31 00:00:00,5
2012-11-06 00:00:00,2
2012-11-05 00:00:00,1

我需要将其转换为ruby，用于RoR项目

我写了以下声明

persons = where(updated_at: start.beginning_of_day..Time.zone.now)
persons = persons.group("date(updated_at)")
persons = persons.select("updated_at, count(*) as total_count")
persons = persons.order("count(updated_at)")

但是，我得到以下错误

PG::Error: ERROR:  column "persons.updated_at" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: SELECT updated_at, count(*) as total_count FROM "persons"  WH...
           ^
: SELECT updated_at, count(*) as total_count FROM "persons"  WHERE ("persons"."updated_at"     BETWEEN '2012-10-17 00:00:00.000000' AND '2012-11-07 14:38:54.674684') GROUP BY     date(persons.updated_at) ORDER BY count(updated_at)

你知道我做错了什么吗？

也许你可以试试

persons = where(updated_at: start.beginning_of_day..Time.zone.now)
persons = persons.group("date(updated_at), updated_at")
persons = persons.select("updated_at, count(*) as total_count")
persons = persons.order("count(updated_at)")

或

或

---

您正在选择

updated\u at

，但您正在

date（updated\u at）

分组。您需要在

updated\u at

（这可能没有任何意义）分组，或者更改您的选择，以便选择

date（updated\u at）

---

换句话说，以Jon Day的第二个例子为例。

我使用了您指定的中间选项，取得了一些成功，但现在我又遇到了另一个错误。ActiveModel:：MissingAttributeError:缺少属性：状态。状态是我的Person类的一个属性。我还尝试将查询细化为，passes=where（更新时间：start.start\u of_day..Time.zone.now）passs=passs.group（“日期（更新时间）”）passs=passs.select（“日期（更新时间），count（*）as total\u count”）。但是现在我得到（对象不支持#inspect）很抱歉，应该是persons not passeshmm也许您可以发布persone模型的代码。因为我认为这与模型代码有关

persons = where(updated_at: start.beginning_of_day..Time.zone.now)
persons = persons.group("date(updated_at)")
persons = persons.select("date(updated_at), count(*) as total_count")
persons = persons.order("count(updated_at)")

persons = persons.find(:all, 
                       :select => "updated_at, count(*) as total_count",
                       :group => "updated_at",
                       :order => "count(updated_at)")