让 MySQL 显示每个用户的评分，然后使用评分对结果进行排序？

Question

问：如何让 MySQL 也显示每个用户的评分，然后使用评分对结果进行排序，desc？

这都是用于游戏天梯的。 weblGames 有每场报告的比赛的结果，并有关于谁赢/输的信息，以及赢家/输家的评分（winner_elo 和 loster_elo）。

这里是表格的部分截图：http://www.ubuntu-pics.de/bild/21059/screenshot_87_RTDZBb.png

当前 MySQL 代码仅使用此表显示（感谢这个地方）每个玩家的姓名和他在最近 x 天内玩的游戏数，.

我想保留该信息，但也能够输出每个玩家当前的 Elo Point（这等于他最近玩的游戏中的获胜者_elo 或失败者_elo。）

这是我目前拥有的代码，它显示了每个玩家以及他/她在 x 天内最近玩过的游戏数量：

SELECT userid, count(*) as cnt 
FROM
(
SELECT winner as userid
from webl_games g 
where (g.reported_on > now() - interval 4 day
UNION ALL 
SELECT loser as userid
from webl_games g 
where g.reported_on > now() - interval 4 day
) t
GROUP BY userid
HAVING COUNT(*) >= 3

Answer 1

SELECT  userid, COUNT(*) as cnt,
        (
        SELECT  CASE t.userid WHEN winner THEN winner_elo ELSE loser_elo END
        FROM    webl_games l
        WHERE   t.userid IN (winner, loser)
        ORDER BY
                reported_on DESC
        LIMIT 1
        ) AS last_elo
FROM    (
        SELECT  winner as userid
        FROM    webl_games g 
        WHERE   (g.reported_on > now() - interval 4 day
        UNION ALL 
        SELECT  loser as userid
        FROM    webl_games g 
        WHERE   g.reported_on > now() - interval 4 day
        ) t
GROUP BY
        userid

这里的子查询可能效率低。

如果是并且您的表有PRIMARY KEY，请将其重写为：

SELECT  userid, cnt,
        (
        SELECT  q2.userid WHEN winner THEN winner_elo ELSE loser_elo END
        FROM    webl_games l
        WHERE   l.id IN (lwin, llose)
        ORDER BY
                reported_on DESC
        LIMIT 1
        )
FROM    (        
        SELECT  userid, COUNT(*) as cnt,
                (
                SELECT  id
                FROM    webl_games l
                WHERE   t.userid = winner
                ORDER BY
                        reported_on DESC
                LIMIT 1
                ) AS lwin,
                (
                SELECT  id
                FROM    webl_games l
                WHERE   t.userid = loser
                ORDER BY
                        reported_on DESC
                LIMIT 1
                ) AS llose
        FROM    (
                SELECT  winner as userid
                FROM    webl_games g 
                WHERE   (g.reported_on > now() - interval 4 day
                UNION ALL 
                SELECT  loser as userid
                FROM    webl_games g 
                WHERE   g.reported_on > now() - interval 4 day
                ) t
        GROUP BY
                userid
        ) q2