MySQL:选择前 n 个最大值?

2021-11-20 00:00:00 max mysql

我对需要返回在特定列上具有最大值的前 N ​​行的查询感到非常困惑.

I am really confused about the query that needing to return top N rows having biggest values on particular column.

例如，如果行 N-1, N, N + 1 具有相同的值.我必须返回 只返回前 N 行 或 前 N + 1 行.

For example, if the rows N-1, N, N + 1 have same values. Must I return just top N or top N + 1 rows.

推荐答案

如果你这样做:

select *
from t
order by value desc
limit N

您将获得前 N 行.

如果你这样做:

select *
from t join
     (select min(value) as cutoff
      from (select value
            from t
            order by value
            limit N
           ) tlim
    ) tlim
    on t.value >= tlim;

或者您可以更简单地将其表述为:

Or you could phrase this a bit more simply as:

select *
from t join
     (select value
      from t
      order by value
      limit N
    ) tlim
    on t.value = tlim.value;

以下是您在概念上想要执行的操作，但它可能不适用于 MySQL:

The following is conceptually what you want to do, but it might not work in MySQL:

select *
from t
where t.value >= ANY (select value from t order by value limit N)

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