## TODO: There has *got* to be another way to do this. It's ridiculous.
  def all_by_tags some_tags
    query = []
    some_tags.each do |tag|
      query << 'SELECT taggings.post_id FROM tags LEFT JOIN taggings ON tags.id = taggings.tag_id WHERE tags.name = ?'
    end

    post_ids = database.query([query.join(" UNION "), some_tags].flatten)
    Post.all(post_ids)
  end