在MySQL中将点赞表与帖子，评论和回复表相关联的有效方法是什么？

Question

I am building a simple social networking website (a personal project of mine to help me understand back-end programming more) and as of the moment I am stuck on how I should tackle the above problem.

Right now I have a table for users, posts, comments, replies, post_likes, comment_likes and reply_likes.

As of the moment my system works as follows:

1. A user creates a post which will then be inserted to the posts table along with that user's id
2. Whenever a user comments on said post, a row is inserted into the comments table along with the user's id and the post's id
3. Whenever a user replies to a comment, it is inserted into the replies table together with that user's id as well as the comment's id in which the reply was made

Enter my likes tables which is structured as so...

post_likes
  post_id
  user_id
  like_state

comment_likes
  comment_id
  user_id
  like_state

reply_likes
  reply_id
  user_id
  like_state

You can probably already tell where I am going with this, but each time a user likes a certain post, comment or reply it gets inserted into its respective like table along with that user's id and a like_state to prevent them from liking again.

This all works fine but I am clearly repeating myself which I know is taboo in the programming world. Which leads us to my question, what exactly can I do to remedy this? Although I came up with an idea, I just can't quite figure out how I can structure my question well enough to be able to get any good results from Google (I am not a native English speaker)

PS the solution I came up with is simply creating just one likes table and each row could either have just a post_id (if the user liked a post), a comment_id (if the user liked a comment) or a reply_id (if the user liked a reply), is that possible?

Answer 1

I think your current tables are good. I think your post, comments and replies has a one to many relationship with the likes. The like should go in separate tables. And you are exactly doing that. If you want to combine the likes into one table, then you will need an extra column to track what is belongs to what. And you will also not able to set the foreign key constrain on that table. So, IMO, you are good at this point.