Naming convention for SQL tables under certain circumstances

Question

I'm currently creating the database schema for a new Rails project and I want to things right, so I better ask!

Imagine this: I have a table called " articles " and these articles should have tags. The thing I would do now is relatively simple. Create another table called " tags " and a third one called " article_tags ". Every article and tag has a unique id and " article_tags " is the mapping table which brings the right article ids and tag ids together.

Tables:

- articles
- tags
- article_tags (mapping)

The "problem" I currently have is this: Not only articles have tags but also my " users " (another table). These tags have to be in two different tables which would then result in some pretty odd naming.

Tables:

- articles
- article_tags (no mapping)
- article_article_tags (mapping???)

- users
- user_tags (no mapping)
- user_user_tags (mapping???)

Do you have any (general) tips how to improve the naming of these tables because what you can see above doesn't make me very happy...

Answer 1

I think you can use polymorphic association to do it, something like this:

class User
  has_many :taggings, as: :taggable
  has_many :tags, through: :taggings
end

class Article
  has_many :taggings, as: :taggable
  has_many :tags, through: :taggings
end

class Tagging
  belongs_to :taggable, polymorphic: true
  belongs_to :tag
end

class Tag
end

So you just need 4 tables: users, articles, taggings, tags.