mysql - 显示最大计数mysql的结果

Question

我需要向用户展示最多的评论。我有两张桌子：

表：用户

ID   |  USERNAME   |    EMAIL
------------------------------
1    |   USER01    |   EMAIL01
2    |   USER02    |   EMAIL02
3    |   USER03    |   EMAIL03
4    |   USER04    |   EMAIL04

表：评论

ID   |  AUTHOR     |    COMMENT
----------------------------------
1    |   USER01    |   COMMENT...
2    |   USER02    |   COMMENT...
3    |   USER01    |   COMMENT...
4    |   USER03    |   COMMENT...

在这个例子中user01，评论最多，但可以说我必须用他们拥有的评论数来计算它们。而且结果我必须向用户显示存储在用户表中的电子邮件。

如何计算并同时检查两个表以返回结果？还是我应该先获取用户信息然后计数？

Answer 1

下面的这个查询处理具有最多评论数的重复行，

SELECT  a.userName
FROM    Users a
        INNER JOIN Comments b
            ON a.username = b.author
GROUP BY    a.userName
HAVING  COUNT(*) = 
    (
        SELECT MAX(totalCount)
        FROM
        (
            SELECT author, COUNT(*) totalCount
            FROM    comments
            GROUP BY author
        ) a
    )

• SQLFiddle 演示
• SQLFiddle 演示（有重复）

但如果你不想处理它，可以简单地通过使用ORDER BY和LIMIT

SELECT  a.userName, COUNT(*) totalCount
FROM    Users a
        INNER JOIN Comments b
            ON a.username = b.author
GROUP BY    a.userName
ORDER BY totalCount DESC
LIMIT 1

• SQLFiddle 演示

Answer 2

select username,email,count(*) as cnt 
from users, comments 
where author = username 
 group by username
 order by cnt desc
 limit 1