SELECT论坛主题与大多数不同的参与者

Question

所以，我正在为我的论坛建立一个奖励系统的成员，并且在选择“与大多数不同参与者的论坛主题”的问题上坚持这个查询。

我已经有了这个查询，可以计算过去24小时内每个论坛主题的帖子数（回复数）。

SELECT poster . * , count( odgovori.id_odgovor ) AS broj, members.username
FROM poster
INNER JOIN odgovori ON ( odgovori.na = poster.id_poster )
INNER JOIN members ON ( poster.od = members.id_member )
WHERE poster.datum = '01.06.09'
GROUP BY odgovori.na, odgovori.od
ORDER BY broj DESC
LIMIT 1 

table poster - forum topics table
table odgovori - replies table 
table members - members table, in this query only used to get topic author's username

Answer 1

SELECT  poster.*, COUNT(DISTINCT odgovori.author) AS different
FROM    poster
JOIN    odgovori
ON      odgovori.na = poster.id_poster
GROUP BY
        poster.id
ORDER BY
        different DESC
LIMIT 1