Question

我想计算同月投票的人数

我的表看起来像：

Table_votes
    ID
    Person_ID
    voteitem_ID
    vote
    Date

表格中的数据如下所示：

1  1  1  2/2/2012
2  1  2  2/2/2012
3  2  1  3/3/2012
4  2  2  3/3/2012
5  3  1  2/12/2012
6  3  2  2/12/2012

我希望查询输出的是2个人在第2个月投票，1个人在第3个月投票

Answer 1

select count(person_id) as person_count
       month(Date) as Month
from table_votes
group by month(Date)

Answer 2

如果您的数据超过一年，则需要考虑到这一点。

试

select 
 count(distinct person_id) as count_personID,
 year(date) as yr,
 month(date) as mo
from
 table_votes
group by
 year(date),
 month(date)