帮助MYSQL查询

Question

在下表中

+-------+-----------------------+ 
| id    | timestamp             | 
+-------+-----------------------+ 
| 1     | 2010-06-10 14:35:30   | 
| 2     | 2010-06-10 15:27:35   | 
| 3     | 2010-06-10 16:39:36   | 
| 4     | 2010-06-11 14:55:30   | 
| 5     | 2010-06-11 18:45:31   | 
| 6     | 2010-06-12 20:25:31   | 
+-------+-----------------------+ 

我希望能够计算日期（时间被忽略）。所以输出应该如下：

+-------+-----------------------+ 
| id    | type         | count  |
+-------+-----------------------+ 
| 1     | 2010-06-10   | 3      |
| 2     | 2010-06-11   | 2      |
| 3     | 2010-06-12   | 1      |
+-------+-----------------------+

对此有什么疑问？

Answer 1

如果结果中没有id列，则可以使用此功能：

SELECT DATE(timestamp) AS type, COUNT(*) AS `count`
FROM sometable
GROUP BY DATE(timestamp)
ORDER BY DATE(timestamp)

Answer 2

SELECT
    DATE(timestamp),
    COUNT(*)
FROM
    My_Table
GROUP BY
    DATE(timestampe)

这不会为每行提供行号。我不知道（为什么？）这很重要。

Answer 3

select date(timestamp) as type, count(*)
from your_table
group by type;

Answer 4

这可能有用......

select DATE(timestamp), count(timestamp)
    from _table
group by timestamp
order by count(timestamp) desc

Answer 5

SELECT count（DATE_FORMAT（时间戳，'％Y-％m-％d /'）），DATE_FORMAT（时间戳，'％Y-％m-％d'） FROM tablename 按DATE_FORMAT分组（时间戳，'％Y-％m-％d'）;

您不能在选择中包含ID，否则计数将会关闭。