完整而简单的解决方案，具有类似的性能，但更短，更灵活的替代方案，目前活跃:

SELECT COUNT(*) FROM stats
-- GROUP BY YEAR(record_date), MONTH(record_date), DAYOFMONTH(record_date)
GROUP BY DATE_FORMAT(record_date, '%Y-%m-%d')

GROUP BY DATE_FORMAT(record_date, '%Y%m')

Note (primarily, to potential downvoters). Presently, this may not be as efficient as other suggestions. Still, I leave it as an alternative, and a one, too, that can serve in seeing how faster other solutions are. (For you can't really tell fast from slow until you see the difference.) Also, as time goes on, changes could be made to MySQL's engine with regard to optimisation so as to make this solution, at some (perhaps, not so distant) point in future, to become quite comparable in efficiency with most others.

如果你想获得一个每月统计数据，每个月的行数按最近一个月排序，那么试试这个:

SELECT count(id),
      YEAR(record_date),
      MONTH(record_date) 
FROM `table` 
GROUP BY YEAR(record_date),
        MONTH(record_date) 
ORDER BY YEAR(record_date) DESC,
        MONTH(record_date) DESC

完整而简单的解决方案，具有类似的性能，但更短，更灵活的替代方案，目前活跃:

SELECT COUNT(*) FROM stats
-- GROUP BY YEAR(record_date), MONTH(record_date), DAYOFMONTH(record_date)
GROUP BY DATE_FORMAT(record_date, '%Y-%m-%d')

如果你想在MySQL中按日期分组，那么使用下面的代码:

 SELECT COUNT(id)
 FROM stats
 GROUP BY DAYOFMONTH(record_date)

希望这为那些要找到这个帖子的人节省了一些时间。

我更喜欢这样优化一年期组的选择:

SELECT COUNT(*)
  FROM stats
 WHERE record_date >= :year 
   AND record_date <  :year + INTERVAL 1 YEAR;

这样你就可以把年份绑定在一起。'2009'，带有命名参数，无需担心添加'-01-01'或单独传入'2010'。

另外，假设我们只是计算行数，id从不为NULL，我更喜欢COUNT(*)而不是COUNT(id)。