从数据库中选择，分组和求和结果 [英] Select, group and sum results from database

问题描述

我有一个数据库，我想总结一些字段。但这不是什么大问题，我想在创建月份的时候将这些字段分组。 ActiveRecord自动创建一个名为created_at的字段。所以我的问题;

以代码更新
如何按月分组结果，然后将每个月的字段总和？

  @hours = Hour.all（：conditions =>user_id =+ @ user.id.to_s，
：group => strftime（'％m'，created_at），
：order =>'created_at DESC'）
  

这是我现在的代码。按月管理分组，但未设法将我需要总结的两个字段mins和salary相加

解决方案通过使用以下方法修复它：select当获取查询时，手动输入选择

  @hours = Hour.all ：conditions =>user_id =+ @ user.id.to_s，
：select =>created_at，SUM（time）time，
：group =>strftime（' m'，created_at），
：order =>'created_at DESC'）
  

I have a database with some fields I'd like to sum. But that's not the big problem, I want to group those fields by the month they were created. ActiveRecord automaticaly created a field named "created_at". So my question; how can I group the result by month, then sum the fields for each month?

Updated with code

@hours = Hour.all(:conditions => "user_id = "+ @user.id.to_s, 
                  :group => "strftime('%m', created_at)",
                  :order => 'created_at DESC')

This is the code I have now. Managed to group by month, but doesn't manage to sum two of my fields, "mins" and "salary" which I need to sum

解决方案

Fixed it by using :select when getting the query, inputing selects manually

@hours = Hour.all(:conditions => "user_id = "+ @user.id.to_s,
                  :select => "created_at, SUM(time) time",
                  :group => "strftime('%m', created_at)",
                  :order => 'created_at DESC')

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