[SQL문제풀기] Revising Aggregations - Averages

문제

Revising Aggregations - Averages | HackerRank

Query the average population of all cities in the District of California.

https://www.hackerrank.com/challenges/revising-aggregations-the-average-function/problem?isFullScreen=true

MySQL, Oracle, MS SQL Server, DB2

내가 작성한 정답

select avg(population) 
from city
where district = 'California';