mysql每天都显示即使没有结果

Question

您好，我有以下查询

SELECT SUM(value1 +value2) AS total  ,created_at
FROM mytable
WHERE created_at 
BETWEEN '2013-10-1' AND '2013-10-19' 
GROUP BY created_at

返回

## total | created_at ##
  2500   | 2013-10-01
  6546   |  2013-10-05

但我想要

## total | created_at ##
   2500  |  2013-10-01
   0     |   2013-10-02
   0     |   2013-10-03
   0     |   2013-10-04
   6546  |   2013-10-05

我想为没有总和的日期返回 0，以便表格显示范围内的每天任何帮助将不胜感激

Answer 1

您可以按照此处描述的方式进行操作:

Get a list of dates between two dates

但这意味着要创建一个额外的表。无论如何，我认为最好在代码级别执行此操作...为什么不这样做呢？