January 2021
Intermediate
240 pages
5h 32m
Japanese
Content preview from 図解まるわかり データベースのしくみ
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128
本の情報を管理するテーブルに、id、title（タイトル）、genre（ジャン
ル）、published̲at（発売日）、memo（メモ）のカラムを設ける場合、そ
れぞれどのようなデータ型や制約・属性を割り当てるのが適切か考えてみ
ましょう。
カラム名 データ型 制約・属性
id
title
genre
published_at
memo
（）
カラム名 データ型 制約・属性
id int AUTO_INCREMENT, NOT NULL
title varchar NOT NULL
genre varchar NOT NULL
published_at datetime NOT NULL
memo text
上の例では、idカラムは数値が入ることを想定して、int型にしてあり
ます。また、1,2, 3,……と連番を自動的に挿入するためにAUTO̲
INCREMENTを設定しています。
titleやgenreカラムは文字列が入ることを想定してvarchar型、published̲
atカラムは日付が入ることを想定してdatetime型にしており、それぞれ空
欄を避けるためにNOTNULL制約を設定してあります。
memoは長い文字列を代入できるようにするためにtext型にしてあり
ます。
やってみよう
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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.