[HackerRank/SQL] Revising Aggregations - Averages

Problem. Revising Aggregations - Averages

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Link.

https://www.hackerrank.com/challenges/japan-population/problem?utm_campaign=challenge-recommendation&utm_medium=email&utm_source=24-hour-campaign

Revising Aggregations - Averages | HackerRank

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Description.

Query the sum of the populations for all Japanese cities in CITY. 

 

CITY 테이블

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Key Point. 

SELECT,

 

SUM,

 

WHERE,

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My Answer. 

SELECT SUM(POPULATION)
FROM CITY
WHERE COUNTRYCODE = 'JPN';

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References.