March 2018
Beginner to intermediate
624 pages
16h 10m
Japanese
Content preview from Head First Python 第2版 ―頭とからだで覚えるPythonの基本
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
さらに
DB-API
DB-API
クローズアップ（
3/3
）
insert
クエリを使って
log
テーブルにサンプルデータを追加してみます。
次に示すクエリを変数
_SQL
に代入し、
cursor.execute
を呼び出してクエリをサーバに送ってみましょう。
>>> _SQL = """insert into log
(phrase, letters, ip, browser_string, results)
values
('hitch-hiker', 'aeiou', '127.0.0.1', 'Firefox', "{'e', 'i'}")"""
>>> cursor.execute(_SQL)
誤解しないでください。上のコマンドは正しく動作します。しかし、テーブルに格納するデータ値は
insert
ご
とに変わるので、このようにデータ値をハードコーディングするこ
とはほとんどありません。
Web
リクエストごと
の詳細を
log
テーブルにロギングするということは、リクエストごとにデータ値が変わるということなので、この
ようにデータをハードコーディングしてしまうと面倒なことになります。
（上のような）ハードコーディングを避けるために、
DB-API
ではクエリ文字列に「データプレースホルダ」を配置
できます。データプレースホルダには、
cursor.execute
の呼び出し時に実際の値が入ります。これにより、ク
エリを実行する直前にクエリに引数として値を渡すことで、異なるデータ値でクエリを再利用できます。クエリ内
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.