unique ID for multi tabel? (MySQL) I have a table 'article' and each of these articles belongs to one of three different topics (topic_a, b and c). I also have a table for each of these topics with various fields. How can I connect these the best way? 

I was thinking that, since every topic has many articles, I would add a topic_ID field to each article, but the ID would not be unique unless I use UUID. Would it make sense to use UUID in this case or is there a better way? 

Another idea was to add three topic ID fields to each article and just fill the appropriate one (topic_a_ID, topic_b_ID,..) and leave the other two empty. But this also seems not right. 

Any suggestions?
Based on your story mine first idea what crosses mine mind was.

**article.** 
 article_id 
 article_name
 ...
 ...

**topic** 
 topic_id
 article_id
 topic_name
 ...
 ...


**topic_has_many_articles** (many to many relation and your connection table)
  topic_id
  article_id


You need to use correct indexing for this to scale well with large datasets.