[HackerRank/Basic Join] Average Population of Each Continent

https://www.hackerrank.com/challenges/average-population-of-each-continent/problem 

Average Population of Each Continent | HackerRank

 

문제

 

풀이

 

SELECT COUNTRY.CONTINENT, TRUNCATE(AVG(CITY.POPULATION),0) FROM COUNTRY
JOIN CITY
ON CITY.COUNTRYCODE = COUNTRY.CODE
GROUP BY COUNTRY.CONTINENT