MySQL 按类型分组，然后按列中的日期范围切片答案

【问题标题】：MySQL grouping by type and then slicing by date ranges in columnsMySQL 按类型分组，然后按列中的日期范围切片
【发布时间】：2013-08-29 20:42:23
【问题描述】：

我有一张这样的桌子：

+----+------+-------------+
| id | type |    date     |
+----+------+-------------+
|  1 | abc  | [some date] |
|  2 | def  | [some date] |
|  3 | abc  | [some date] |
|  4 | abc  | [some date] |
|  5 | xyz  | [some date] |
+----+------+-------------+

我正在尝试这样的结果：

+------+-----------+------------+-----------+
| type | last year | last month | last week |
+------+-----------+------------+-----------+
| abc  |      5489 |        355 |       101 |
| def  |      2235 |        115 |        59 |
| xyz  |      1998 |        180 |        75 |
+------+-----------+------------+-----------+

其中数字表示给定日期范围内相应类型的行数。

我已经尝试过这些方法：

SELECT type, 
    (SELECT count(*) FROM table WHERE [date last year]) AS `last year`,
    (SELECT count(*) FROM table WHERE [date last month]) AS `last month`,
    (SELECT count(*) FROM table WHERE [date last week]) AS `last week`
FROM table
GROUP BY type

但是对于每种类型返回相同的数字（给定日期范围内的总数）。当我将GROUP BY 语句添加到子选择时，我收到一条错误消息，指出子选择返回了多行。

那么我该如何解决呢？

非常感谢您！

【问题讨论】：

标签： mysql sql count group-by subquery

【解决方案1】：

你想要条件聚合：

SELECT type, 
       sum([date last year]) AS `last year`,
       sum([date last year]) AS `last year`,
       sum([date last month]) AS `last month`,
       sum([date last week]) AS `last week`
FROM table
GROUP BY type;

也就是说，将您的逻辑放入sum()——您的问题表明您理解该逻辑。

【讨论】：