Group and sum array of hashes by date

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Group and sum array of hashes by date

I have an array of hashes like this: [{:created=>Fri, 22 Jan 2014 13:02:13 UTC +00:00, :amount=>20}, {:created=>Fri, 27 Jan 2014 13:14:57 UTC +00:00, :amount=>15}, {:created=>Fri, 27 Jan 2014 14:42:40 UTC +00:00, :amount=>10}, {:created=…

MySQL中group by , sum , case when then 的使用

在我们使用数据库的时候,可能会遇到需要进行统计的情况. 比如需要统计一下,下表中各个年份的胜负场数. 遇到这样的情况,我们应该怎么办呢? 在mysql中我们可以使用group by sum case when 来解决这个问题,sql语句如下: select date_year,sum(case when win_lose = '胜' then 1 else 0 end) win,sum(case when win_lose = '负' then 1 else 0 end) losefrom s…

[Swift通天遁地]五、高级扩展-(6)对基本类型：Int、String、Array、Dictionary、Date的扩展

★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★➤微信公众号:山青咏芝(shanqingyongzhi)➤博客园地址:山青咏芝(https://www.cnblogs.com/strengthen/)➤GitHub地址:https://github.com/strengthen/LeetCode➤原文地址:https://www.cnblogs.com/strengthen/p/10241650.html ➤如果链接不是山青咏芝的博客园地址,则可能是爬取作者的文章…

[转]LINQ: Using INNER JOIN, Group and SUM

本文转自:https://stackoverflow.com/questions/530925/linq-using-inner-join-group-and-sum SELECT T1.Column1, T1.Column2, SUM(T3.Column1) AS Amount FROM T1 INNER JOIN T2 ON T1.T1ID = T2.T1ID INNER JOIN T3 ON T2.T3ID = T3.T3ID GROUP BY T1.Column1, T1.Column2…

17-[JavaScript]- 内置对象 Array，String，Date，Math

1.Array数组 <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title></title> </head> <body> </body> <script type="text/javascript"> //列表 js 数组容器装东西 //创建数组 //1.字面量方式创建 (推荐大…

1.Two Sum (Array; HashTable)

Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that…

1. Two Sum [Array] [Easy]

Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Example: input: nums = [2, 7, 11, 15…