MySQL ORDER BY另一个表中用户的总行数

Question

假设，我想显示按用户发送的大量邮件排序的用户列表。

我有2个表：Users和Messages

我有10个用户

用户A发送了20条消息（在消息表中有20行）

SELECT * FROM messages WHERE user='A'


User B sent 17 msgs    
User C sent 19    
User D sent 13

等等。

我想要一个查询，按照发送的总消息顺序列出用户。像：

1. A (20 msgs)
2. C (19 msgs)
3. B (17 msgs)
4. D (13 msgs)

我努力但我找不到任何查询来执行此操作。请帮忙。提前谢谢。

Answer 1

SELECT user, COUNT(*) FROM messages GROUP BY user ORDER BY count(*) DESC;

Answer 2

如果要打印名称加入用户表，

select user_name, count(*) from users inner join messages m on users.userid=m.messageid group by userid order by count(*) desc;

Answer 3

您可以使用alias：

进行排序

SELECT user, COUNT(1) as cnt
FROM Messages 
GROUP BY user 
ORDER BY cnt DESC;

或position：

SELECT user, COUNT(1) as cnt
FROM Messages 
GROUP BY user 
ORDER BY 2 DESC;