[SQL문제풀기 - Advent of SQL 2025 🎅] 연도별 순매출 구하기

문제

solvesql.com

https://solvesql.com/problems/yearly-net-sales/

내가 작성한 오답

PostgreSQL

select to_char(purchased_at,'yyyy') as year, sum(total_price)-sum(discount_amount) net_sales
from transactions
where not is_returned 
group by to_char(purchased_at,'yyyy')
order by year;

SQLite

select strftime('%Y',purchased_at)+0 as year, sum(total_price)-sum(discount_amount) net_sales
from transactions
where not is_returned 
group by strftime('%Y',purchased_at)+0
order by year;

select cast(strftime('%Y',purchased_at) as integer) as year, sum(total_price)-sum(discount_amount) net_sales
from transactions
where not is_returned 
group by cast(strftime('%Y',purchased_at) as integer)
order by year;

내가 작성한 정답

MySQL

select year(purchased_at) year, sum(total_price)-sum(discount_amount) net_sales
from transactions
where not is_returned 
group by year(purchased_at)
order by year;

PostgreSQL

select extract(year from purchased_at) as year, sum(total_price)-sum(discount_amount) net_sales
from transactions
where not is_returned 
group by extract(year from purchased_at)
order by year;

SQLite

select strftime('%Y',purchased_at) as year, sum(total_price)-sum(discount_amount) net_sales
from transactions
where not is_returned 
group by strftime('%Y',purchased_at)
order by year;