private function _getJoins( array $attributes, $prefix )
	{
		$iface = 'MW_Common_Criteria_Attribute_Interface';
		$sep = $this->_getKeySeparator();
		$name = $prefix . $sep . 'id';

		if( isset( $attributes[$name] ) && $attributes[$name] instanceof $iface ) {
			return $attributes[$name]->getInternalDeps();
		}
		else if( isset( $attributes['id'] ) && $attributes['id'] instanceof $iface ) {
			return $attributes['id']->getInternalDeps();
		}

		return array();
	}