[HackerRank] Average Population of Each Continent

https://www.hackerrank.com/challenges/average-population-of-each-continent/problem?isFullScreen=true&h_r=next-challenge&h_v=zen&h_r=next-challenge&h_v=zen 

Average Population of Each Continent | HackerRank

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:

 

 

[My Answer]

SELECT B.CONTINENT, Floor(avg(A.POPULATION))
FROM CITY A
INNER JOIN
COUNTRY B
ON A.COUNTRYCODE = B.CODE
GROUP BY B.CONTINENT