Example of how to wire up a database adapter with ZF2

db.local.php

<?php

// config/db.local.php

return array(
    'db' => array(
        'database' => 'name_of_your_database',
        'username' => 'user',
        'password' => 'password',
        'hostname' => '127.0.0.1',
    ),
    'db_another' => array(
        'database' => 'name_of_your_database',
        'username' => 'user',
        'password' => 'password',
        'hostname' => '127.0.0.1',
    ),    
);

module.config.php

<?php

// module/MyNamespace/config/module.config.php

return array(
  
    // ...
  
    'db' => array(
        'driver' => 'Pdo_Mysql',
        'characterset' => 'utf8',
        'database' => '',
        'username' => '',
        'password' => '',
        'hostname' => '',
    ),
    'db_another' => array(
        'driver' => 'Pdo_Mysql',
        'characterset' => 'utf8',
        'database' => '',
        'username' => '',
        'password' => '',
        'hostname' => '',
    ),    
    
    // ...    
);

Module.php

<?php

// module/MyNamespace/Module.php

namespace MyNamespace;

use Zend\ModuleManager\Feature\ConfigProviderInterface;
use Zend\ModuleManager\Feature\ServiceProviderInterface;
use Zend\ServiceManager\ServiceManager;

class Module implements ConfigProviderInterface, ServiceProviderInterface
{

    /**
     * Returns an array with module-specific configuration options.
     *
     * @return array
     */
    public function getConfig()
    {
        return include __DIR__ . '/config/module.config.php';
    }

    /**
     * Returns an array with service configuration options.
     *
     * @return array
     */
    public function getServiceConfig()
    {
        return array(
            'factories' => array(
                /**
                 * Uses the factory class
                 * 
                 * @see Zend\Db\Adapter\AdapterServiceFactory
                 */
                'DatabaseAdapter' => 'Zend\Db\Adapter\AdapterServiceFactory',
                /**
                 * Uses a closure
                 */
                'AnotherDatabaseAdapter' => function (ServiceManager $serviceManager) {
                    
                    $config = $serviceManager->get('Config');
                    
                    return new \Zend\Db\Adapter\Adapter($config['db_another']);
                },
            ),
        );
    }

}