<?php
// Doctrine_Manager controls all the connections 

$manager = Doctrine_Manager::getInstance();

// open first connection

$conn = $manager->openConnection(new PDO("dsn","username","password"), "connection 1");

// open second connection

$conn2 = $manager->openConnection(new PDO("dsn2","username2","password2"), "connection 2");

$manager->getCurrentConnection(); // $conn2

$manager->setCurrentConnection("connection 1");

$manager->getCurrentConnection(); // $conn

// iterating through connections

foreach($manager as $conn) {
    
}
?>
