/*
    SELECT c.name
    FROM products_categories_map m
    LEFT JOIN products p ON m.product = p.id
    LEFT JOIN companies c ON c.id = p.company
    WHERE m.category = 2
    GROUP BY c.name
    */
		$categories = Doctrine_Query::create() -> select("c.name")
		                                       -> from("ProductsCategories m")
		                                       -> leftJoin("Product p")
		                                       -> leftJoin("Company c ON c.id = p.company")
		                                       -> where("m.category = ?")
		                                       -> groupBy("c.name")
		                                       -> execute(array(1));

/* Code throws exception: 
Catchable fatal error: Argument 1 passed to Doctrine_Hydrator_RecordDriver::getElement() must be an array, null given, called in C:\Server\www\tts\app\lib\model\doctrine\Doctrine\Hydrator.php on line 128 and defined in C:\Server\www\tts\app\lib\model\doctrine\Doctrine\Hydrator\RecordDriver.php on line 106
*/