May 2022
Beginner to intermediate
448 pages
13h 7m
Korean
book
밑바닥부터 시작하는 데이터 과학 데이터 분석을 위한 파이썬 프로그래밍과 수학·통계 기초
by Joel Grus, Hangyeol Kim, Seongju Ha, Eunjung Park
Content preview from 밑바닥부터 시작하는 데이터 과학 데이터 분석을 위한 파이썬 프로그래밍과 수학·통계 기초
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from Scratch
385
칭되는 행을 찾을 수 있게 된다. 또한
user_id
인덱스에 유일성(
unique
) 조건이
걸려 있다면, 중복된 값을 생성하려고 할 때 에러가 발생하도록 만들 수 있다.
데이터베이스의 각 테이블에는 하나 또는 그 이상의 인덱스가 있을 수 있고,
이 덕분에 중요한 열의 행을 빠르게 찾을 수 있으며, 효율적으로 테이블을
JOIN
하거나 열 또는 열의 조합에 유일성 제약 조건을 추가할 수 있다.
한편 인덱스를 만들고 사용하는 것은 (어떤 데이터베이스를 사용하냐에 따라
다르기는 하지만) 일종의 흑마법과 같다. 하지만 데이터베이스를 자주 다룰 거
라면 제대로 배워 볼 가치가 있다.
24.10
쿼리 최적화
SQL
에 관심 있는 사용자를 찾는 쿼리문은 다음과 같다.
SELECT users.name
FROM users
JOIN user
_
interests
ON users.user
_
id = user
_
interests.user
_
id
WHERE user
_
interests.interest = 'SQL'
NotQuiteABase
로 이 쿼리를 쓸 수 있는 방법은 (적어도) 두 가지가 있다.
user_
interests
테이블을 필터링한 후
JOIN
을 하거나
( user
_
interests
.where(lambda row: row["interest"] ...
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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.