Select SQL 子查询中的最大值

Question

我有如下查询：

select * 
from 
    (select 
         centre_name, sum(qty) as number1 
     from 
         (select 
              exchange_from_centre_id as cenid, 
              count(exchange_from_centre_id) as qty
          from 
              as2.exchange
          group by 
              exchange_from_centre_id

          union all

          select 
              exchange_to_centre_id as cenid, 
              count(exchange_to_centre_id) as qty
          from 
              as2.exchange
          group by 
              exchange_to_centre_id), as2.centre c
where 
    c.centre_id = cenid
group by 
    centre_name);

这是结果：中心名称和交换数量

Alice Springs Desert Park   1
Werribee Open Range Zoo     6
Kruger National Park        2
Johannesburg Zoo            4
Australia Zoo               2
SanWild Wildlife Sanctuary  5

我想 select 这个结果（第 2 行）的最大值，除了排序和选择第 1 行之外，任何人都可以帮助我进行 MAX 查询。

Answer 1

SQL Fiddle Demo

我使用你的结果查询而不是大查询来简化示例。

我将您的示例更新为有 2 行，最大值为 6。

您在 select 中计算最大值，然后加入原始 table 以带来所有匹配该值的行

SELECT *
FROM (SELECT MAX(Score) Score
      FROM Table1) as mV
INNER JOIN Table1 t
   ON mv.Score = t.Score

Answer 2

应该可行

select * from (select centre_name, sum(qty) as number1 from 
                (select exchange_from_centre_id as cenid, count(exchange_from_centre_id) as qty
                from as2.exchange
                group by exchange_from_centre_id
            union all
                select exchange_to_centre_id as cenid, count(exchange_to_centre_id) as qty
                from as2.exchange
                group by exchange_to_centre_id), as2.centre c
where c.centre_id = cenid
group by centre_name) where number1 = (select max(number1) from (select centre_name, sum(qty) as number1 from 
                (select exchange_from_centre_id as cenid, count(exchange_from_centre_id) as qty
                from as2.exchange
                group by exchange_from_centre_id
            union all
                select exchange_to_centre_id as cenid, count(exchange_to_centre_id) as qty
                from as2.exchange
                group by exchange_to_centre_id), as2.centre c
where c.centre_id = cenid
group by centre_name));

Select SQL 子查询中的最大值

Select max value in subquery in SQL

sql

subquery

max