MySQL:选择前n个最大值？

Question

我真的很困惑于需要返回具有最大值的顶部N行的查询.

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

Answer 1

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;

或者你可以更简单地说这个:

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

以下是概念上您想要做的事情,但它可能在MySQL中不起作用:

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

Answer 2

使用以下 SQL 查询。

SELECT salary FROM salesperson 
ORDER BY salary DESC
LIMIT 2,1