>>> from inyoka.forum.views import *
>>> topics = Topic.objects.order_by('-last_post')
>>> topics = topics.annotate(p_count=Count('posts')).filter(p_count=1)
>>> topics = topics.distinct()
>>> topics = topics.values_list('id', flat=True)
>>> str(topics.query)
'SELECT DISTINCT `forum_topic`.`id`, `forum_topic`.`last_post_id` FROM `forum_topic` LEFT OUTER JOIN `forum_post` ON ( `forum_topic`.`id` = `forum_post`.`topic_id` ) GROUP BY `forum_topic`.`id` HAVING COUNT(`forum_post`.`id`) = 1 ORDER BY `forum_topic`.`last_post_id` DESC'