ActiveRecord for PHP5.2

I used ActiveRecord of Yii framework.

Doctrine?

Here, something more similar to ActiveRecord of Rails and CodeIgniter www.crystal-project.net

Here's another encountered such a thing www.phpactiverecord.org/
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"php-activerecord is an open source ORM library based on the ActiveRecord pattern. It aims to massively simplify the interactions with your database and eliminate the chore of hand written SQL for common operations. Unlike other ORMs, you do not need to use any code generators nor maintain mapping files for your tables. This library was inspired by Ruby on Rails' implementation and therefore borrows many of its conventions and ideas. The best place to get started is by checking out the Guides below! The library is licensed under the MIT License and so you are completely free to do whatever you want with it."
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Though not yuzal, so can not say anything, but you may want to look at it.

Approached a couple of times "voraciously" to the choice of an ActiveRecord class PHP.
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Doctrine
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The size of the library, a lot of files, many layers for an "honest" ActiveRecord, complete abstraction from SQL functions and specific DB. One instance of ORM is enough memory. Var_dump is better for him not to do it, will tear the screen.
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>> www.michaelpaul.com.br/introducao-orm-php-doctrine.html
>> ini_set('memory_limit', '256M');
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Does not suit me, now am using ActiveRecord from LIMB, the whole framework is not necessary to include. All that is in Doctrine, in addition to specific DQL, there is in the LIMB. Memory consumes less.
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Read more: habrahabr.ru/blogs/php/104106/

That's old, works for php4, the ADOdb library, you may also be interested:
\rphplens.com/lens/adodb/docs-active-record.htm