Try RedBean, its requires:

• No configuration
• No database (it creates everything on the fly)
• No models
• etc.

It even does all the locking and transactions for you and monitors performance in the background. (Heck! it even does garbage collection….) Best of all… you don’t have to write a single… line of code… Jesus this, ORM layer, saved me ass!

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

There are only two good ones: Doctrine and Propel. We favor Doctrine, and it works well with Symfony. However if you’re looking for database support besides the main ones you’ll have to write your own code.

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

Another great open source PHP ORM that we use is PHPSmartDb. It is stable and makes your code more secure and clean. The database functionality within it is hands down the easiest I have ever used with PHP 5.3.

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

Look at http://code.google.com/p/lworm/ . It is a really simple, but powerful, lightweight ORM system for PHP. You can also easily extend it, if you want.

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

Look into Doctrine.

Doctrine 1.2 implements Active Record. Doctrine 2+ is a DataMapper ORM.

Also, check out Xyster. It’s based on the Data Mapper pattern.

Also, take a look at DataMapper vs. Active Record.

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

You should check out Idiorm and Paris.

NOTE: This answer was originally posted at StackOverflow.com by th3mus1cman

Axon ORM is part of the Fat-Free Framework – it features an on-the-fly mapper. No code generators. No stupid XML/YAML configuration files. It reads the database schema directly from the backend, so in most CRUD operations you don’t even have to extend a base model. It works with all major PDO-supported database engines: MySQL, SQLite, SQL Server/Sybase, Oracle, PostgreSQL, etc.

/* SQL */
CREATE TABLE products (
    product_id INTEGER,
    description VARCHAR(128),
    PRIMARY KEY (product_id)
);

/* PHP */
// Create
$product=new Axon('products'); // Automatically reads the above schema
$product->product_id=123;
$product->description='Sofa bed';
$product->save(); // ORM knows it's a new record

// Retrieve
$product->load('product_id=123');
echo $product->description;

// Update
$product->description='A better sofa bed';
$product->save(); // ORM knows it's an existing record

// Delete
$product->erase();

Most of all, the plug-in and accompanying SQL data access layer are just as lightweight as the framework: 14 KB (Axon) + 6 KB (SQLdb). Fat-Free is just 55 KB.

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