我应该如何为像SO和yahoo答案的用户创建一个积分系统？（PHP）

Question

I am creating a voting system for a Q&A site project in which if a user asks a question, he/she losses -5 points; answer a question +5, vote a question +1, etc. (kind of like SO and yahoo answers)

-->To create the basic arithmetic, I have a "users_points" table that relates the user_id and their total points.

+---+---------+
| 1 | 100     |
+---+---------+
| 2 | 54      |
+---+---------+

-->Basically if the users does certain task, it would + or - the points. How do I prevent users from say voting an answer up 100 times. ex: I want a user to be only able to vote once per question, etc.

Answer 1

You should create a votes table that has the columns: user_id, question_id, delta. Delta is the value of the vote, which should be 1 or -1 (this way you can just do a SUM(delta) to find a question's point value).

To get the uniqueness, create a unique index on (user_id, question_id).