如何按日期对列的日期类型时间戳进行分组

Question

数据库是mysql。该表喜欢：

Create table Persons (_id int8 primary key, name varchar, birthday long); 

生日是生日的时间戳。

所以我想选择按日期分组的数据，这意味着结果应该是一天的一条记录

select sum(_id) from Persons group by ....

有谁可以帮助我？

Answer 1

试试这种方式，

select sum(_id) FROM Persons GROUP BY DATE_FORMAT(birthday, '%Y%m%d')

Answer 2

也许：

select sum(_id) from Persons group by DATE_FORMAT(FROM_UNIXTIME(birthday), '%d-%m-%Y')

Answer 3

select sum(_id) from Persons group by date_format(birthday,'%y-%m-%d')