https://www.hackerrank.com/challenges/african-cities/problem
Given the CITY and COUNTRY tables, query the names of all cities where the CONTINENT is 'Africa'.
Note: CITY.CountryCode and COUNTRY.Code are matching key columns.
Input Format:
The CITY and COUNTRY tables are described as follows:
<내 코드>
SELECT city.NAME
FROM city
INNER JOIN country
ON city.CountryCode = country.Code
WHERE country.continent = 'Africa';