经典均大于小于，每个都的问题

看到关键字均大于小于，每个都的问题 这种可以看看正选还是反选比较简单

查询所有国家人口均≤25000000的大洲，及其国家名（name）和人口（population）

反选法
select
name
,continent
,population
from world
where continent not in (select distinct continent
                        from world
                        where population >25000000
                                            )

还有我自己的正选法，明显就比别人复杂↓

SELECT 
NAME,
population,
continent, 
FROM world 
WHERE continent =(SELECT 
continent 
FROM (SELECT 
name,
population,
continent, 
rank() over (PARTITION by continent ORDER BY population DESC) k
from world
GROUP BY continent,population,name) a WHERE k=1 and population<=25000000)