Question

我有一个Mysql数据库，我有两个表格，其架构为：

CREATE TABLE IF NOT EXISTS `items` (
  `id` int(10) unsigned NOT NULL,
  `name` varchar(200) NOT NULL,
  PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;

CREATE TABLE IF NOT EXISTS `sold_records` (
  `id` int(10) unsigned NOT NULL,
  `item_id` int(10) NOT NULL,
  `count` int(10) NOT NULL,
  `sold_at` timestamp NOT NULL,
  PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;

如您所见，我有一些项目和一些销售记录，我希望通过SQL查询得到这样的结果：

item_name   sold_count_at_today sold_count_at_yestoday ... sold_count_at_today - 30day
item_1                x                   x            ...        x
item_2                x                   x            ...        x
...
item_n                x                   x            ...        x

有人可以就SQL查询得到这样的结果提出一些建议吗？

您可以在SQLFiddle。

中对其进行调试

Answer 1

不幸的是，我认为你必须用一堆案例函数来做这件事，比如：

SELECT i.name,
CASE WHEN CAST(sold_at AS date) = '2017-10-31' THEN 'X' ELSE NULL END AS '2017-10-31',
CASE WHEN CAST(sold_at AS date) = '2017-11-01' THEN 'X' ELSE NULL END AS '2017-11-01'
...
FROM items i
INNER JOIN sold_records r
ON i.id = r.item_id

我在你设置的小提琴上试过这个。你可以在这里查看：

http://sqlfiddle.com/#!9/92f796/19

Answer 2

select a.name as item_name,
count(b.sold_at = (DATE_FORMAT(FROM_UNIXTIME(current_timestamp), '%e %b %Y'))) as
sold_count_at_today,
count((b.sold_at = (DATE_FORMAT(FROM_UNIXTIME(current_timestamp -1), '%e %b %Y')))) as sold_count_at_yesterday,
count((b.sold_at = (DATE_FORMAT(FROM_UNIXTIME(current_timestamp- 30), '%e %b %Y')))) as 30_day
from items a, sold_records b
where a.id = b.item_id 
group by a.name;

试试这个。 http://sqlfiddle.com/#!9/92f796/23/0假设今天是当前的时间戳。

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2 个答案: