August 2022
Beginner to intermediate
436 pages
9h 43m
Korean
Content preview from SQL로 시작하는 데이터 분석
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157
3
장
시계열 분석
증감률(%)
월
그림
3-17
서점업 매출의 전월 대비 증감률
더 적절한 분석법은 올해와 작년의 동일 시기 매출을 비교하는 방법입니다. 이어서
SQL
로 현
재 월 매출과 전년 동월 매출을 비교하는 방법을 알아봅시다.
3.5.2
구간 비교: 작년과 올해 비교
특정 시간 구간의 데이터를 이전 시간 구간의 데이터와 비교해보면 계절성을 확인하는 데 유용
합니다. 이때, 이전 시간 구간은 지난주의 같은 요일이 될 수도 있고, 작년의 같은 달이 될 수도
있습니다.
구간 비교를 하려면, 현재 값을 비교하고자 하는 시간 단위로
PARTITION
BY
절을 적용하고
lag
함수를 사용합니다. 예제에서는 월 매출별로 전년 동월 매출과 비교해봅니다. 예를 들어,
1
월 매출은 작년
1
월 매출과 비교하고,
2
월 매출은 작년
2
월 매출과 비교합니다.
158
SQL로 시작하는 데이터 분석
우선,
date
_
part
함수에
‘
month
’
인자를 사용하면 해당 날짜의 월을 가져와서 정숫값으로 반
환한다는 점을 떠올려봅시다.
SELECT
sales_month
,date_part(‘month’,sales_month) ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.