select c.name from city c left join country c1 on c.countrycode = c1.code where c1.continent = 'africa';

SELECT p1.NAME FROM CITY AS p1 INNER JOIN COUNTRY AS p2 ON p1.COUNTRYCODE = p2.CODE WHERE p2.continent = 'Africa'

select city.name from city,country where city.countrycode=country.code and country.continent like "Africa";

MYSQL

SELECT CITY.NAME
FROM CITY, COUNTRY
WHERE CITY.COUNTRYCODE = COUNTRY.CODE AND COUNTRY.CONTINENT = 'Africa';

SELECT CITY.NAME FROM CITY LEFT JOIN COUNTRY ON CITY.COUNTRYCODE = COUNTRY.CODE WHERE COUNTRY.CONTINENT = "Africa";