I need to access database from phtml (view) in zend. how can i do that?
$stmt = $db->query('SELECT * FROM mcommerce_cart');
Well, you should not do this (it's bad practice). Recommend way is to access DB via models. You can pass data to view from Controller, Zend_View_Helper or (also no so recommeneded) via direct call to model.
But if you really want to access DB in View than you can get Default Adapter by calling
$db = Zend_Db_Table::getDefaultAdapter();