Choosing a primary key for a many-many relationship

Question

I am trying to simulate a site similar to StackOverflow. He has a set of users and questions, as well as user voting on questions. Each user can have only one vote on each issue.

What should be the structure of my table "VotesOnQuestions":

• Should I have a VoteID auto-generated column?
• How to disconnect at the user circuit level from several votes to a question?
• Should I use (UserID, QuestionID) as primary key instead of VoteID column?

Answer 1

Use the primary key UserID, QuestionID .

This will ensure compliance with your requirements and optimize your search.