protected function _dsn() {
		$host = $this->_config['host'];

		if ($host[0] === '/') {
			return sprintf(
				'mysql:unix_socket=%s;dbname=%s',
				$host,
				$this->_config['database']
			);
		}
		list($host, $port) = explode(':', $host) + array(1 => "3306");

		return  sprintf(
			'mysql:host=%s;port=%s;dbname=%s',
			$host,
			$port,
			$this->_config['database']
		);
	}