HackerRank: [SQL Basic Join] (2/8) AFRICAN CITIES | distinct & inner join in SQL

I started studying SQL from a very famous site - HackerRank. Here I will try to provide multiple approaches & solutions to the same problem. It will help you learn and understand SQL in a better way.

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Recommended SQL Courses:

1. Udemy: SQL - MySQL for Data Analytics and Business Intelligence
2. LinkedIn: Master SQL for Data Science
3. edX: Databases: Advanced Topics in SQL
4. edureka: SQL Essentials Training & Certification
5. Coursera: Learn SQL Basics for Data Science
6. Eduonix: SQL Queries

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SQL Problem Statement:

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:

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Solution: Using INNER JOIN OR JOIN (MySQL Query):

SELECT DISTINCT B.NAME
FROM COUNTRY A
JOIN CITY B
ON A.CODE = B.COUNTRYCODE
WHERE A.CONTINENT = 'Africa'
ORDER BY B.NAME;

NOTE: 

1. DISTINCT keyword is used to get the unique records only. It removes duplicate records.
   
   
2. JOIN and INNER JOIN are the same in SQL. It returns the records that have matching values in both tables.

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Expected Output:

Alberton
Brakpan
Kempton Park
Klerksdorp
Libreville
Qina
Uitenhage
Warraq al-Arab

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-Akshay P Daga