Hello coders, today we are going to solve Population Census HackerRank Solution in SQL.
Problem
Given the CITY and COUNTRY tables, query the sum of the populations of all cities where the CONTINENT is ‘Asia’.
Note: CITY.CountryCode and COUNTRY.Code are matching key columns.
Input Format
The CITY and COUNTRY tables are described as follows:
| Field | Type |
|---|---|
| ID | NUMBER |
| NAME | VARCHAR2(17) |
| COUNTRYCODE | VARCHAR2(3) |
| DISTRICT | VARCHAR2(20) |
| POPULATION | NUMBER |
| Field | Type |
|---|---|
| CODE | VARCHAR2(3) |
| NAME | VARCHAR2(44) |
| CONTINENT | VARCHAR2(13) |
| REGION | VARCHAR2(25) |
| SURFACEAREA | NUMBER |
| INDEPYEAR | VARCHAR2(5) |
| POPULATION | NUMBER |
| LIFEEXPECTANCY | VARCHAR2(4) |
| GNP | NUMBER |
| GNPOLD | VARCHAR2(9) |
| LOCALNAME | VARCHAR2(44) |
| GOVERNMENTFORM | VARCHAR2(44) |
| HEADOFSTATE | VARCHAR2(32) |
| CAPITAL | VARCHAR2(4) |
| CODE2 | VARCHAR2(2) |
Solution – Population Census in SQL
MySQL
select sum(city.population) from country left join city on country.code = city.countrycode where country.continent = 'Asia'
Disclaimer: The above Problem (Population Census) is generated by Hacker Rank but the Solution is Provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.
SELECT sum(city.population)
FROM city
INNER JOIN country
ON city.countrycode = country.code where continent=’asia’;
select sum(city.population) from city join country on city.countrycode=country.code
where country.continent=’Asia’;
This will also work why you confuse other.