sql - 正确使用 count(*) 和 group by 函数

Question

在 sql 中，您可以将 GROUP BY 函数与国家之类的列一起使用吗？（这将是一个 char/varchar）

SELECT country, population, COUNT(*) AS count_cities
FROM list_of_cities
GROUP BY country;

写这个更好的方法是什么？

Answer 1

SELECT country, SUM(population) AS country_population, COUNT(*) AS count_cities 
FROM list_of_cities 
GROUP BY country;