Question

我有一个表'Country'（带有SQLWorkbench的演示版），带有属性：'name'和'IndepYear'。

我想找到更多国家变得独立的一年，我对他们的名字不感兴趣。

此查询有效。

SELECT Nest.IndepYear, Nest.conta 
  FROM (Select IndepYear,count(IndepYear) AS conta 
   FROM country  GROUP BY IndepYear) Nest 
    WHERE Nest.conta = (Select max(conta) FROM (SELECT IndepYear,count(IndepYear) AS conta 
     FROM country GROUP BY IndepYear)Nest2)

输出

IndepYear   Conta
1960        18
1991        18

是否有更聪明，更易读或更有效的方法来做到这一点？

编辑：感谢您的答案到目前为止，但我有兴趣获得仅顶级结果。我的意思是获得所有前n行和那些行。

Answer 1

这远非完美，但可能会为您提供有关如何改进查询的一些想法：

select IndepYear, count(*) 
from country 
group by IndepYear 
having count(*) = (
  select count(*) from country group by IndepYear order by count(*) desc limit 1
)

Answer 2

如果我理解你的问题，下面的SQL应该可以解决问题：

SELECT IndepYear, count(IndepYear) conta
FROM Countries
GROUP BY IndepYear
ORDER By count(IndepYear) DESC

请参阅SQL Fiddle以获取完整的解决方案。

基本SQL。有没有更好的方法来使用聚合函数？

2 个答案: