Question

我不确定那里是否有这样的问题，找不到我的解决方案，很抱歉，如果这是重复的话：我有一张日期表：

  |date (date)| tax (numeric) |  (stuff in brackets is the type)
  |2012-12-12 | 5.00          |
  |2012-12-12 | 10.00         |
  |2012-12-13 | 2.00          |

我希望我的输出看起来像这样：

  |date (date)| tax (numeric) |  (stuff in brackets is the type)
  |2012-12-12 | 15.00         |
  |2012-12-13 | 2.00          |

我正在考虑做一个CTE类型的查询，因为在数据库中，我将事物存储为没有时区的日期时间，以及一堆税这是我的查询的开始：

 with date_select as
 (
 select CAST(r.datetime as DATE), sum(r.tax) as tax
 from suezensalon.receipt r
 where r.datetime between '2012-12-12 00:00:00' and '2012-12-18 23:59:59'
 group by r.datetime  
 order by r.datetime
 )

这给了我顶级表格。做这个的最好方式是什么？是通过'平均日期'吗？

Answer 1

这就是最终的工作：

 with date_select as
 (
 select CAST(r.datetime as DATE), sum(r.tax) as tax
 from suezensalon.receipt r
 where r.datetime between '2012-12-12 00:00:00' and '2012-12-18 23:59:59'
 group by r.datetime  
 order by r.datetime 
 ) 
 select extract(Month from datetime) || '-' || extract(Day from datetime) || '-' ||   extract(Year from datetime) as Date, sum(tax)
 from date_select
 group by Date
order by Date;

Answer 2

我认为最简单的选择，并且最有可能在索引存在的情况下表现良好，将是这样的：

SELECT
    datetime::date as "Date",
    sum(tax)
  FROM suezensalon.receipt
  WHERE datetime >= '2012-12-12 00:00:00'
    AND datetime <  '2012-12-19 00:00:00'
  GROUP BY datetime::date
  ORDER BY "Date";

PostgreSQL选择数字总和，按日期分组

2 个答案: