select a.name from city as a inner join country as b where a.countrycode = b.code AND b.continent = 'Africa';

select CITY.NAME from CITY inner join COUNTRY on CITY.COUNTRYCODE=COUNTRY.CODE where CONTINENT="Africa";

SELECT distinct(CITY.NAME) FROM CITY INNER JOIN COUNTRY on CITY.COUNTRYCODE = COUNTRY.CODE WHERE COUNTRY.CONTINENT="Africa";

INNER JOIN METHOD

SELECT CITY.NAME FROM CITY INNER JOIN COUNTRY ON CITY.COUNTRYCODE=COUNTRY.CODE WHERE COUNTRY.CONTINENT="AFRICA";

WITHOUT INNER JOIN METHOD

SELECT CITY.NAME FROM CITY,COUNTRY WHERE CITY.COUNTRYCODE=COUNTRY.CODE AND COUNTRY.CONTINENT="AFRICA";

Works in MySql:

select city.name from city, country 
where city.countrycode = country.code 
and country.continent='africa';

or,

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