[해커랭크 SQL] Aggregation - Revising Aggregations - Averages

❓ Question
https://www.hackerrank.com/challenges/revising-aggregations-the-average-function

Revising Aggregations - Averages | HackerRank

❗ Answer

SELECT AVG(population)
    FROM city
    WHERE district='California';

📌 Discussion

• where로 조건에 맞는 레코드 불러온 후 avg로 집계