August 2022
Beginner to intermediate
436 pages
9h 43m
Korean
Content preview from SQL로 시작하는 데이터 분석
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151
3
장
시계열 분석
self
-
JOIN
으로 카티션
JOIN
을 수행하면 윈도우 함수를 사용하지 않고도 위와 동일한 결과를
생성합니다. 다음 예제에서는 같은 연도끼리만 집계하기 위해 두 테이블의
sales
_
month
필드
에서 연도를 기준으로
JOIN
을 수행해 매년 윈도우를 재설정합니다. 또한,
JOIN
조건을 추가해
b
테이블의
sales
_
month
가
a
테이블의
sales
_
month
보다 작거나 같은 날짜의 결과만 반환하
도록 합니다.
1992
년
1
월에는
b
테이블의 오직
1992
년의
1
월의 행만 조건을 만족하고,
1992
년
2
월에는
b
테이블의
1992
년
1
월과
2
월이 조건을 만족하며,
1992
년
3
월에는
b
테이블의
1992
년
1
월,
2
월,
3
월이 조건을 만족합니다.
SELECT
a.sales_month, a.sales
,
sum
(b.sales)
as
sales_ytd
FROM
retail_sales a
JOIN
retail_sales b
on
date_part(‘year’,a.sales_month) = date_part(‘year’,b.sales_month)
and
b.sales_month <= a.sales_month
and
b.kind_of_business = ‘Women’’s clothing stores’
WHERE
a.kind_of_business ...
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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.