SELECT教程5中的Sqlzoo SELECT

Question

我的问题是:

Germany (population 80 million) has the largest population of the countries in Europe. Austria (population 8.5 million) has 11% of the population of Germany.

Show the name and the population of each country in Europe. Show the population as a percentage of the population of Germany.

我的答案:

SELECT name,CONCAT(ROUND(population/80000000,-2),'%')
FROM world
WHERE population = (SELECT population
                    FROM world
                      WHERE continent='Europe')

我做错了什么？
谢谢。

Answer 1

问题不完整，取自here

这就是答案

SELECT 
  name, 
  CONCAT(ROUND((population*100)/(SELECT population 
                                 FROM world WHERE name='Germany'), 0), '%')
FROM world
WHERE population IN (SELECT population
                     FROM world
                     WHERE continent='Europe')

我想知道子查询，因为从OP的问题来看还不清楚(至少对我来说)。原因是“世界”表(顾名思义，我必须承认)包含所有世界国家，而我们只对欧洲国家感兴趣。而且，德国的人口必须从数据库中检索出来，因为它并不是80.000.000。如果使用该数字，您将获得101％的德国人口。