https://www.hackerrank.com/challenges/japan-population/problem?isFullScreen=true
Japan Population | HackerRank
Query to the sum of the populations of all Japanese cities in CITY.
www.hackerrank.com
코드설명
SUM을 활용합니다.
ORACLE 코드
SELECT SUM(POPULATION)
FROM CITY
WHERE COUNTRYCODE = 'JPN';