GROUP BY YEAR(record_date), MONTH(record_date)

查看MySQL中的日期和时间函数。

下面的查询在Oracle Database 12c Release 12.1.0.1.0中为我工作

SELECT COUNT(*)
FROM stats
GROUP BY 
extract(MONTH FROM TIMESTAMP),
extract(MONTH FROM TIMESTAMP),
extract(YEAR  FROM TIMESTAMP);

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.

试试这个

SELECT COUNT(id)
FROM stats
GROUP BY EXTRACT(YEAR_MONTH FROM record_date)

EXTRACT(unit FROM date)函数更好，因为使用较少的分组，并且函数返回一个数字值。

分组时的比较条件将比DATE_FORMAT函数(返回字符串值)快。尝试使用函数|字段返回非字符串值的SQL比较条件(WHERE, HAVING, ORDER BY, GROUP BY)。

我试着使用上面的“WHERE”语句，我认为它是正确的，因为没有人纠正它，但我错了;经过一些搜索，我发现这是WHERE语句的正确公式，所以代码变成这样:

SELECT COUNT(id)  
FROM stats  
WHERE YEAR(record_date) = 2009  
GROUP BY MONTH(record_date)

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。