[MySQL/HackerRank] Average Population of Each Continent

https://www.hackerrank.com/challenges/average-population-of-each-continent/problem?isFullScreen=true 

Average Population of Each Continent | HackerRank

문제

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: 

Code

SELECT COUNTRY.CONTINENT, FLOOR(AVG(CITY.POPULATION))
FROM COUNTRY
JOIN CITY ON COUNTRY.CODE = CITY.COUNTRYCODE
GROUP BY COUNTRY.CONTINENT