[프로그래머스] 카테고리 별 도서 판매량 집계하기

문제

제출

SELECT category as CATEGORY,sum(sales) as TOTAL_SALES
from book as a
join book_sales as b
on a.book_id=b.book_id
where sales_date like '2022-01%'
group by category
order by category asc

또 다른 답

where sales_date like '2022-01%'
'2022-01' 문자열을 포함하는 행만 필터링 되도록했다.

날짜 조건 비교문을 다르게 쓸 수 있다.

1. 달만 추출해서 1월인 데이터 추출

SELECT category as CATEGORY,sum(sales) as TOTAL_SALES
from book as a
join book_sales as b
on a.book_id=b.book_id
where MONTH(sales_date)='01'
group by category
order by category asc

2. 부등호 사용

SELECT category as CATEGORY,sum(sales) as TOTAL_SALES
from book as a
join book_sales as b
on a.book_id=b.book_id
WHERE SALES_DATE >= '2022-01-01' AND SALES_DATE <= '2022-01-31'
group by category
order by category asc

3. DATE_FORMAT 사용

SELECT category as CATEGORY,sum(sales) as TOTAL_SALES
from book as a
join book_sales as b
on a.book_id=b.book_id
WHERE DATE_FORMAT(SALES_DATE,'%Y-%m')='2022-01'
group by category
order by category asc