In the following example we make a user management system where

# Each user and group are entities
# User is an entity of type 0
# Group is an entity of type 1
# Each entity (user/group) has 0-1 email
# Each entity has 0-* phonenumbers
# If an entity is saved all its emails and phonenumbers are also saved
# If an entity is deleted all its emails and phonenumbers are also deleted
# When an entity is created and saved a current timestamp will be assigned to 'created' field
# When an entity is updated a current timestamp will be assigned to 'updated' field
# Entities will always be fetched in batches

<code type='php'>
class Entity extends Doctrine_Record 
{
    public function setUp() 
    {
        $this->ownsOne('Email', 'Entity.email_id');
        $this->ownsMany('Phonenumber', 'Phonenumber.entity_id');
        $this->setAttribute(Doctrine::ATTR_LISTENER, new EntityListener());
    }
    public function setTableDefinition() 
    {
        $this->hasColumn('name', 'string', 50);
        $this->hasColumn('loginname', 'string', 20);
        $this->hasColumn('password', 'string', 16);

    }
}

</code>

yep       class Group extends Entity
{
    public function setUp() 
    {
        parent::setUp();
        $this->hasMany('User', 'Groupuser.user_id');
        $this->setInheritanceMap(array('type'=>1));
    }
}
class User extends Entity 
{
    public function setUp() 
    {
        parent::setUp();
        $this->hasMany('Group', 'Groupuser.group_id');
        $this->setInheritanceMap(array('type'=>0));
    }
}
class Groupuser extends Doctrine_Record 
{
    public function setTableDefinition() 
    {
        $this->hasColumn('group_id', 'integer');
        $this->hasColumn('user_id', 'integer');
    }
}

class Phonenumber extends Doctrine_Record 
{
    public function setTableDefinition() 
    {
        $this->hasColumn('phonenumber', 'string', 20);
        $this->hasColumn('entity_id', 'integer');
    }
}
class Email extends Doctrine_Record 
{
    public function setTableDefinition() 
    {
        $this->hasColumn('address', 'string', 150, 'email|unique');
    }
}
class EntityListener extends Doctrine_EventListener 
{
    public function onPreUpdate(Doctrine_Record $record) 
    {
        $record->updated = time();
    }
    public function onPreInsert(Doctrine_Record $record) 
    {
        $record->created  = time();
    }
}

// USER MANAGEMENT SYSTEM IN ACTION:

$manager = Doctrine_Manager::getInstance();

$conn = $manager->openConnection(new PDO('DSN','username','password'));

$user = new User();

$user->name = 'Jack Daniels';
$user->Email->address = 'jackdaniels@drinkmore.info';
$user->Phonenumber[0]->phonenumber = '123 123';
$user->Phonenumber[1]->phonenumber = '133 133';
$user->save();

$user->Group[0]->name = 'beer lovers';
$user->Group[0]->Email->address = 'beerlovers@drinkmore.info';
$user->Group[0]->save();