How to create access to database with zend in magento
As you already know, magento use Zend_Db to make MySql queryes.
To get the Zend_Db object for your queryes anywhere use this code:
<?php $zendDb = Mage::getSingleton('core/resource')->getConnection('catalog_read'); ?>
In order to make queryes in magento read the Zend manual here.