php 推荐mysql数,为什么不推荐使用PHP的mysql_函数？

比眉伴天荒 2023-01-24 03:29 87阅读 0赞

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Playing Devil's Advocate a little here as I stopped using these functions a while ago, but the question is genuine and probably matters to a lot of SO users.

We all know that using mysql\_ functions in the wrong way can be very dangerous, it can leave your website vulnerable, etc. but used correctly these functions can be protected against SQL injection and are actually a fair bit faster than the newer PDO functions.

Bearing all this in mind, why have the mysql\_ functions been deprecated?

解决方案

The mysql extension is ancient and has been around since PHP 2.0, released 15 years ago (!!); which is a decidedly different beast than the modern PHP which tries to shed the bad practices of its past. The mysql extension is a very raw, low-level connector to MySQL which lacks many convenience features and is thereby hard to apply correctly in a secure fashion; it's therefore bad for noobs. Many developers do not understand SQL injection and the mysql API is fragile enough to make it hard to prevent it, even if you're aware of it. It is full of global state (implicit connection passing for instance), which makes it easy to write code that is hard to maintain. Since it's old, it may be unreasonably hard to maintain at the PHP core level.

The mysqli extension is a lot newer and fixes all the above problems. PDO is also rather new and fixes all those problems too, plus more.

Due to these reasons\* the mysql extension will be removed sometime in the future. It did its job in its heyday, rather badly, but it did it. Time has moved on, best practices have evolved, applications have gotten more complex and require a more modern API. mysql is being retired, live with it.

Given all this, there's no reason to keep using it except for inertia.

\* These are my common sense summary reasons; for the whole official story, look here: https://wiki.php.net/rfc/mysql\_deprecation

Choice quotes from that document follow:

The documentation team is discussing the database security situation,

and educating users to move away from the commonly used ext/mysql

extension is part of this.

Moving away from ext/mysql is not only about security but also about

having access to all features of the MySQL database.

ext/mysql is hard to maintain code. It is not not getting new

features. Keeping it up to date for working with new versions of

libmysql or mysqlnd versions is work, we probably could spend that

time better.