Question

我试图在某个行标准之前和之后仅选择相邻的N和M行，用于关注用户个人得分的高分表（与具有类似得分N以上和M以下的玩家相比）。

scores
-------
id:int
username:varchar(120)
score:int

注意：每个用户名都有多个分数。高分数据库只是一个分数转储

因此，仅获取前十名全球分数：SELECT max(score),username FROM scores GROUP BY username, ORDER BY score DESC

但是，我正试图为任意用户做这件事 - 大多数用户都没有幸运地进入前10名......

如何在某个用户的分数上方引用N行和M行，以便在用户得分之上和之下提取10个分数？

Answer 1

要获得高于用户的N个结果，假设所有分数都是不同的：

select s.*
from scores
where s.score > (select s.score from scores where username = $username)
order by score desc
limit N;

要获得M分数低于给定用户分数：

select s.*
from scores
where s.score < (select s.score from scores where username = $username)
order by score asc
limit M;

得分相同会带来一点挑战。以下内容将上述两个与union all结合起来并解决了这个问题：

(select s.*
 from scores s cross join
      (select * from scores where username = $username) u
 where s.score > u.score or
       s.score = u.score and s.id > u.id
 order by s.score desc, s.id desc
 limit N
) union all
(select s.*
 from scores s cross join
      (select * from scores where username = $username) u
 where s.score < u.score or
       s.score = u.score and s.id < u.id
 order by s.score, s.id
 limit M
)

MySQL - 选择特定行标准的行

1 个答案: