Back in fall 2001, I was looking for a database abstraction package that would make my companies application framework RDBMS independent. The goal was to reduce database specific code to zero. The only package I found that offered such features was Metabase. But Metabase had a somewhat uncomfortable API that was partly a result of the compatibility to PHP3. This also made Metabase slower than it needed to be for our purposes, since we did not need PHP3 compatibility. Nonetheless, we decided that Metabase is our only option. But even after adding a performance enhancing patch to Metabase we felt that we were giving up too much performance. We met with the author of Metabase at the International PHP Conference 2001 and we talked about the benefits of having something like Metabase as part of the PEAR project. Shortly afterwards a discussion began once more in the PEAR mailing list about the potential benefits of a merge of PEAR DB and Metabase. After much discussion at my company we decided to take up this task. After several months of hard work we now have the first stable release of MDB.
早在 2001 年的秋天，我就在寻找一种可能能够让我公司的程序框架与 RDBMS 独立的数据库抽象包。这个目标是把特定数据库相关的代码数量减少到零。我发现提供这样的功能的唯一的一个包是 Metabase。但是 Metabase有一些部分是因为为了和 PHP3 兼容的让人不舒服的 API。尽管如此，我们决定 Metabase 是我们唯一的选择。但是即使是在给 Metabase 增加了一个性能改进的补丁之后，我们仍然感到我们放弃了太多的性能。我们在 2001 年的 PHP 国际会议上碰到了 Metabase 的作者，并且我们谈论了让像 Metabase 这样的东西成为 PEAR 工程一部分的好处。后来不久，在 PEAR 邮件列表上就 PEAR DB 和 Metabase 融合的可能的好处又开始了一场讨论。在我们公司进行了许多讨论之后，我们决定承担这个任务。数个月的艰辛工作之后，我们现在有了 MDB 的第一个稳定的 release。
What does MDB do for you?
MDB 给你提供了什么？
MDB combines most of the features of PEAR DB and Metabase. Actually, the only feature that is missing is PEAR DB's feature of returning an object as a result set. This feature was dropped because the feature's usage never became abundant but the performance penalty was quite apparent. A lot of development time was spend on making the API as intuitive as possible as well. Finally, MDB provides this functionality at a very high level of performance that is at least as fast as PEAR DB and much faster than Metabase. Here is the list of the most important features:
MDB 结合了 PEAR DB 和 Metabase 的大部分特性。实际上，PEAR DB 的特性中唯一不再存在的是作为结果集返回一个对象。我们放弃了这个特性是因为这个特性不常用而且对于性能的损失是非常明显的。许多开发上的时间用在了使得 API 尽可能的好用。最终，MDB 非常高地提供了这些功能至少和 PEAR DB 一样快而且比 Metabase 快很多。这些最重要地特性的列表：
OO-style API
prepared queries emulation
full data type abstraction for all data passed to and from the database (including LOB support)
transaction support
database/table/index/sequence creation/dropping/altering
RDBMS independent database schema management
Integrated into the PEAR framework (PEAR Installer, PEAR error handling etc.)
OO 风格的 API
预准备的查询模拟
给所有传递进来以及从数据库中取出的数据的完全的数据类型抽象（包括 LOB 支持）
事务支持
数据库/表/索引/序列创建/抛弃/改变
RDBMS 无关的数据库 schema 管理
继承进 PEAR 框架（PEAR 安装程序，PEAR 错误处理等）
So how does it work?
那么它如何使用呢？
MDB provides some very advanced abstraction features. It is important to keep in mind that these features are optional. But using them is critical in writing RDBMS independent PHP applications. An example of how the basics of MDB work can be found under Links & Literature at the end of the article. As stated earlier, the focus of the article is to introduce the features that set MDB apart from other database abstraction layers for PHP. You can find example scripts for all code examples found in this article on the CD that is packaged with this issue.
MDB 提供了一些非常先进的抽象特性。记住这些特性只是供选择的是很重要的。但是在编写 RDBMS 无关的 PHP 程序时使用它们是非常重要的。一个展示使用 MDB 是多么简单的例子在文章的结尾的 "链接和文献" 部分。如前面所说，文章的焦点是介绍使得 MDB 与其他 PHP 数据库抽象层不同的那些特性。你可以在随本期文章一同包装的 CD 中找到所有这些例子脚本的代码。
But first we will need to get MDB installed. This is actually quite easy using the PEAR installer. I cannot cover the entire PEAR Installer within this article but I hear the next issue will talk about great details about all the ins and outs of the PEAR framework. There is work going on to make the Installer work on Windows but the support is still a bit flaky. For *nix systems you will need a CGI version of PHP installed on your system and simply run the following command:
但是，首先我们需要把 MDB 安装上去。使用 PEAR 安装程序这其实非常容易。我不能在这篇文章中完整的讲述 PEAR 安装程序但是我听说下一期将非常详细的讨论 PEAR 框架的里里外外。让安装程序运行于 Windows 的工作在进行当作但是支持仍然有一点古怪。对于 *nix 系统你需要 PHP 的 CGI 版本安装在了你的系统并且简单地运行下面地命令：
lynx -source go-pear.org|php
After completing the installation process you simply need to type one more command and you are all set.
在安装完成之后你只需要再输入一行命令那么就全部搞定了。
pear install MDB