Algorithm
Problem Name: Sql -
In this HackerRank Functions in SQL problem solution,
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: 
Code Examples
#1 Code Example with MySQL
Code -
MySQL
SELECT CITY.NAME
FROM CITY, COUNTRY
WHERE CITY.COUNTRYCODE = COUNTRY.CODE AND COUNTRY.CONTINENT = 'Africa';