August 2022
Beginner to intermediate
436 pages
9h 43m
Korean
Content preview from SQL로 시작하는 데이터 분석
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228
SQL로 시작하는 데이터 분석
시작 날짜인
first
_
term
대신 지속 연수를 기준으로 코호트를 정의해도 좋습니다. 여러 시간
구간에서 상대적으로 최근에 들어온 고객의 비율, 중기간 고객의 비율, 장기간 고객의 비율을
구해 비교해보면 좋은 인사이트가 도출되기도 합니다. 이러한 접근으로 의원의 재임 연수가 시
간에 따라 어떻게 변화하는지 알아봅시다.
먼저, 연도별로 각 의원의 누적 재임 연수를 계산합니다. 의원이 선거에서 떨어지는 등 연임
하지 못해서 임기 사이에 공백이 생기기도 합니다. 이를 처리하려면 우선 서브쿼리에서 연도
별로
12
월
31
일을 기준으로 의원이 재임 중인지 확인합니다. 그리고
count
윈도우 함수와
unbounded
preceding
and
current
row
범위를 지정해 처음 행부터 현재 행까지의 연도
수, 즉 의원별 누적 재임 연수를 구합니다.
SELECT
id_bioguide, date
,
count
(date)
over
(
partition
by
id_bioguide
order
by
date
rows
between
unbounded
preceding
and
current
row
)
as
cume_years
FROM
(
SELECT
distinct
a.id_bioguide, b.date
FROM
legislators_terms ...
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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.
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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.