HackerRank - Average Population of Each Continent

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: 

 

 

 

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Answer

SELECT country.continent
    , FLOOR(AVG(city.population))
FROM city
    INNER JOIN country ON city.countrycode = country.code
GROUP BY country.continent

 

 

Result

Asia 693038
Europe 175138
Oceania 109189
South America 147435
Africa 274439