最大函数问题与其他列的值

Question

我有以下MySQL查询：

Select match_static_id, comments as last_comment, max(timestamp)
from comments as c 
group by match_static_id;

我有关于比赛的评论表，我希望得到每场比赛的最新评论。 所以我使用max（timestamp）和group by（match_static_id），但我的问题是我得到的最大时间戳由match_static_id分组，但我得到其他评论（不是最大时间戳的评论） 我的查询是否以错误的方式排序？

Answer 1

我不是mysql的专家，但我能感觉到这个问题。这可能是因为注释不属于group by，它会返回匹配match_static_id的所有行。我建议改写像：

select match_static_id, (select Comment from comments c where c.timestamp =max(a.timestamp)) as last_comment, max(timestamp) from comments group by match_staic_id

或

select c.match_static_id, c.comments as last_comment, c.timestamp from comments c inner join (Select max(timestamp) as ts from comments group by match_static_id) temp c.timestamp = temp.ts