I’ve been developing Pork.dbObject on my own. (A simple PHP ORM and Active Record implementation)
The main reason is that I find most ORMs too heavy.

The main thought of Pork.dbObejct is to be light-weight and simple to set up. No bunch of XML files, just one function call in the constructor to bind it, and an addRelation or addCustomRelation to define a relation to another dbObject.

Give it a look: Pork.dbObject

NOTE: This answer was originally posted at StackOverflow.com by SchizoDuckie

Try Doctrine2. It’s probably the most powerful ORM tool for PHP. I’m mentioning it separately from Doctrine 1, because it’s a completely different piece of software. It’s been rewritten from scratch, is still in beta phase, but it’s usable now and developed.

It’s a very complex ORM, but well designed. Lot of magic from original Doctrine 1 disappeared. It provides a complete solution, and you can write your own ORM on top of Doctrine2 or use just one of its layers.

NOTE: This answer was originally posted at StackOverflow.com by tomp

I just started with Kohana, and it seems the closest to Ruby on Rails without invoking all the complexity of multiple configuration files like with Propel.

NOTE: This answer was originally posted at StackOverflow.com by Zak

Have a look at the LEAP ORM for Kohana. It works with a bunch of databases, including DB2, Drizzle, Firebird, MariaDB, SQL Server, MySQL, Oracle, PostgreSQL, and SQLite. With a simple autoload function, it can work with almost any PHP framework. The source code is on GitHub at https://github.com/spadefoot/kohana-orm-leap. You can checkout LEAP’s tutorials online.

The ORM library works with non-integer primary keys and composite keys. Connections are managed via a database connection pool and it works with raw SQL queries. The ORM even has a query builder that makes building SQL statements super simple.

NOTE: This answer was originally posted at StackOverflow.com by Matthew

My friend Kien and I have improved upon an earlier version of an ORM that he had written prior to PHP 5.3. We have essentially ported over Ruby on Rails’ Active Record to PHP. It is still lacking some key features we want such as transactions, composite primary key support, a few more adapters (only MySQL and SQLite 3 work right now). But, we are very close to finishing this stuff up. You can take a look at PHP ActiveRecord with PHP 5.3.

NOTE: This answer was originally posted at StackOverflow.com by Jacques Fuentes

I have had great experiences with Idiorm and Paris. Idiorm is a small, simple ORM library. Paris is an equally simple Active Record implementation built on Idiorm. It’s for PHP 5.2+ with PDO. It’s perfect if you want something simple that you can just drop into an existing application.

NOTE: This answer was originally posted at StackOverflow.com by Sander Marechal

I work on miniOrm. Just a mini ORM, for using Object Model & MySQL Abstraction Layer as simply as possible. Hope it may help you : http://jelnivo.fr/miniOrm/

NOTE: This answer was originally posted at StackOverflow.com by Cédric Mouleyre

NotORM

include "NotORM.php";
 $pdo = new PDO("mysql:dbname=software");
 $db = new NotORM($pdo);
 $applications = $db->application()
->select("id, title")
->where("web LIKE ?", "http://%")
->order("title")
->limit(10)
;
foreach ($applications as $id => $application) {
echo "$application[title]\n";
}

NOTE: This answer was originally posted at StackOverflow.com by Charlie Chai

Agile Toolkit has its own unique implementation of ORM/ActiveRecord and dynamic SQL.

Introduction: http://agiletoolkit.org/intro/1

Syntax (Active Record):

$emp=$this->add('Model_Employee');
$emp['name']='John';
$emp['salary']=500;
$emp->save();

Syntax (Dynamic SQL):

$result = $emp->count()->where('salary','>',400)->getOne();

While Dynamic SQL and Active Record/ORM is usable directly, Agile Toolkit further integrates them with User Interface and jQuery UI. This is similar to JSF but written in pure PHP.

$this->add('CRUD')->setModel('Employee');

This will display AJAXified CRUD with for Employee model.

NOTE: This answer was originally posted at StackOverflow.com by romaninsh

Brazilian ORM: http://www.hufersil.com.br/lumine. It works with PHP 5.2+. In my opinion, it is the best choice for Portuguese and Brazilian people, because it has easy-to-understand documentation and a lot of examples for download.

NOTE: This answer was originally posted at StackOverflow.com by Paulo Araujo

MicroMVC has a 13 KB ORM that only relies on a 8 KB database class. It also returns all results as ORM objects themselves and uses late static binding to avoid embedding information about the current object’s table and meta data into each object. This results in the cheapest ORM overhead there is.

It works with MySQL, PostgreSQL, and SQLite.

NOTE: This answer was originally posted at StackOverflow.com by Xeoncross

Sado is a simple PHP ORM package, easy to use, and offers video tutorials

NOTE: This answer was originally posted at StackOverflow.com by Shay Anderson

There’s a fantastic ORM included in the QCubed framework; it’s based on code generation and scaffolding. Unlike the ActiveRecord that’s based on reflection and is generally slow, code generation makes skeleton classes for you based on the database and lets you customize them afterward. It works like a charm.

NOTE: This answer was originally posted at StackOverflow.com by Alex Weinstein

If you are looking for an ORM that implements the Data Mapper paradigm rather than Active Record specifically, then I would strongly suggest that you take a look at GacelaPHP.

Gacela features:

• Data mapper
• Foreign key mapping
• Association mapping
• Dependent mapping
• Concrete table inheritance
• Query object
• Metadata mapping
• Lazy & eager loading
• Full Memcached support

Other ORM solutions are too bloated or have burdensome limitations when developing anything remotely complicated. Gacela resolves the limitations of the active record approach by implementing the Data Mapper Pattern while keeping bloat to a minimum by using PDO for all interactions with the database and Memcached.

NOTE: This answer was originally posted at StackOverflow.com by Noah Goodrich

Try PdoMap. Wikipedia claims that is inspired by Hibernate. Since I never used Hibernate, I cannot judge :), but I would say from my experience that is good and fast ORM that is easy to implement, with a less steep learning curve that other ORMs.

NOTE: This answer was originally posted at StackOverflow.com by aromawebdesign.com

Looked at Syrius ORM. It’s a new ORM, the project was in a development stage, but in the next mouth it will be released in a 1.0 version.

NOTE: This answer was originally posted at StackOverflow.com by biancardi

A really good simple ORM is MyActiveRecord. MyActiveRecord documentation. I have been using it a lot and can say it’s very simple and well tested.

NOTE: This answer was originally posted at StackOverflow.com by Szymon Wygnański

Tried the ORM of Flourish library.

NOTE: This answer was originally posted at StackOverflow.com by eaguilar

Try PHP ADOdb.

I can’t say it’s the best, because I haven’t used the others. But it’s fast, it supports Memcached and caching.

And it’s waaaay faster than Zend Framework’s DB/Select.

NOTE: This answer was originally posted at StackOverflow.com by Salam Fall

If you are looking for an ORM, like Hibernate, you should have look at PMO.

It can be easily integrated in an SOA architecture (there is only a webservice classe to develop).

NOTE: This answer was originally posted at StackOverflow.com by anonymous