Doctrine is a great ORM and DBAL library to use with your Symfony2 application. But occasionally it can feel like a black box, where magic just happens. In those cases it would be good to have a look at what actually happens.
Luckily, Doctrine can easily be configured to log its doings. From a container aware object, such as your controllers or commands, you can enable logging like this.
$this
->get('doctrine')
->getConnection()
->getConfiguration()
->setSQLLogger(new \Doctrine\DBAL\Logging\EchoSQLLogger());
This will set up EchoSQLLogger to do your logging for you, which results in every query and its parameters being printed with echo and var_dump(). Quick, easy and not too dirty!
Supressed logging
You could also use the DebugStack logger, which will record the queries without printing them. Just set it up similarly to as previously shown.
$logger = new \Doctrine\DBAL\Logging\DebugStack();
$container
->get('doctrine')
->getConnection()
->getConfiguration()
->setSQLLogger($logger);
And after some Doctrine usage, access your logged activity in the queries property.
var_dump($logger->queries);
Custom logging
If that is not enough, you can always create your own logger with whatever crazy functionality you need. As long as it implements the SQLLogger interface it can be injected with the setSQLLogger method.