Hackerrank | MySQL | Average Population of Each Continent

Average Population of Each Continent

Problem

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.

 

 

 

SELECT country.continent, FLOOR(AVG(city.population))
FROM city
    LEFT JOIN country ON city.countrycode = country.code
GROUP BY country.continent
HAVING country.continent IS NOT NULL

SELECT COUNTRY.Continent, FLOOR(AVG(CITY.Population))
FROM City
    INNER JOIN Country ON CITY.CountryCode = COUNTRY.Code
GROUP BY COUNTRY.Continent