MySQL:查询有关系的排行榜 [英] MySQL: Querying a leaderboard with ties

问题描述

我知道这是一个受欢迎的话题，但是我仍然找不到想要的东西.我想查询一张桌子

I know this is a popular topic, but I still haven't found quite what I'm looking for. I'd like to query one table

BOOKS_READ
id
user_id
book_id

格式化列出阅读最多书籍的用户排行榜.当用户阅读一本书时，与该书ID和用户ID相匹配的记录将被记录到books_read表中.

to format a leaderboard of users who have listed the most books as having been read. When a user reads a book, a record matching the book id and the user id gets logged into the books_read table.

是否可以从1开始并考虑平局来对查询结果进行排名?

Is it possible to rank the results of this query, starting at 1, and with consideration of ties?

SELECT user_id, COUNT(*) AS book_count 
FROM books_read 
GROUP BY user_id 
ORDER BY book_count DESC LIMIT 10

如果出现平局，我想在结果中列出一个'='符号.

In the event of a tie, I would like to list an '=' sign in the results.

例如，

rank  user_id  book_count  
=1    30       121
=1    17       121
 2    101      119
=3    11       104
=3    91       104

非常感谢您的帮助！我不介意使用PHP来处理其中的一些问题，但是我对学习针对此类问题的直接SQL解决方案非常感兴趣:-)

Many thanks for any help! I don't mind using PHP to handle some of it, but I'm very interested in learning straight SQL solutions to these kinds of things :-)

推荐答案

SELECT GROUP_CONCAT(user_id, book_count
FROM (
    SELECT user_id, COUNT(*) AS book_count 
    FROM books_read 
    GROUP BY user_id 
    ORDER BY book_count DESC
) AS T1
GROUP BY book_count
ORDER BY book_count

给你

user_id  book_count  
30,17       121
101         119
11,91       104

然后您可以使用PHP解析关系.

Which you can then use PHP to parse for ties.

<?php
$rank = 1;

while ($row = mysql_fetch_assoc($result)) {
    $users = explode(',', $row['user_id'];
    foreach ($users as $user) {
        echo 'Rank: ' . $rank . ' ' . $user . "\n;
    }
    $rank++;
}

?>

这篇关于MySQL:查询有关系的排行榜的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！