August 2022
Beginner to intermediate
436 pages
9h 43m
Korean
Content preview from SQL로 시작하는 데이터 분석
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107
3
장
시계열 분석
위 코드에서
date
_
part
함수를 추가로 사용하면
age
함수에서 계산된 결과에서 월 단위 인터
벌 값만 가져옵니다.
SELECT
date_part(‘month’,age(‘2020-06-30’,’2020-01-01’))
as
months
;
months
------
5.0
이처럼 빼기 연산으로 두 날짜 간 인터벌을 계산하는 작업은 분석 업무에 아주 유용합니다. 한
편 더하기 연산은 빼기 연산과 동일하게 동작하지 않습니다. 날짜와 날짜를 더할 수는 없으며,
3
날짜에 더하기 연산을 수행하려면 인터벌이나 특별한 함수를 사용해야 합니다.
예를 들어, 인터벌
‘
7
days
’
를 사용해 특정 날짜에
7
일을 더해봅시다.
SELECT
date(‘2020-06-01’) + interval ‘7 days’
as
new_date;
new_date
-------------------
2020-06-08 00:00:00
몇몇 데이터베이스에서는 다음 코드처럼 인터벌 문법을 사용하지 않고 숫자만 입력해도 자동
으로 인터벌로 변환하지만, 인터벌을 명시하면 코드가 이해하기 쉬워지고 다른 데이터베이스
에서도 잘 동작합니다.
SELECT
date(‘2020-06-01’) + 7
as
new_date;
new_date
-------------------
2020-06-08 ...
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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.
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.