[MySQL/HackerRank] Population Census

https://www.hackerrank.com/challenges/asian-population/problem?isFullScreen=true 

Population Census | HackerRank

문제

Given the CITY and COUNTRY tables, query the sum of the populations of all cities where the CONTINENT is 'Asia'.

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

Input Format

The CITY and COUNTRY tables are described as follows: 

Code

SELECT SUM(CITY.POPULATION)
FROM CITY
JOIN COUNTRY ON CITY.COUNTRYCODE = COUNTRY.CODE
WHERE COUNTRY.CONTINENT = 'ASIA'