[HackerRank] Average Population of Each Continent

Given the CITY and COUNTRY tables, query the names of all the continents (COUNTRY.Continent) and their respective average city populations (CITY.Population) rounded down to the nearest integer.

Note: CITY.CountryCode and COUNTRY.Code are matching key columns.

Input Format

The CITY and COUNTRY tables are described as follows:

CITY와 COUNTRY를 조인 -> 대륙별로 GROUP BY -> FLOOR로 평균 인구수 내림

select country.continent, floor(avg(city.population))
from city inner join country
on city.countrycode = country.code
group by country.continent