Question

In my database are 2 tables: “books” and “users”. I’m displaying all the books on a page and would like the option for a user to click a little link “I’ve Read This”, similar to Facebook’s Like function with statuses. The user could click that they’ve read the book or unclick to “unread” the book. Other users logged in could also see who has read what. I’m questioning my approach and would like to get feedback on other directions to take for something like this.

What I had in mind was to have a field in the “users” table, maybe something like “books_read”, in which I would store an array of values (book_id’s). On the frontend where all the books are displayed, I would query the “books_read” field and if a value matched the current book_id, then underneath that book would be something like “User X has read this”.

In short, I would store an array of “book_id”s in the “users” table to collect what books each user has read. I would pull this array and compare IDs to each book queried, and if there is a match, output that the user has read that book.

Am I missing something or maybe not looking at a cleaner approach?

Answer 1

In a RDBMS such as MySQL, it’s rarely ever a good idea to store lists in a field, especially when you know you will be looking for specific pieces in the list later on. The database can not take advantage of an index by doing that.

Instead, you should make an additional table that links users and books read. Optionally, you could call it *users_books* and move read in to its own column.

users_booksread
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user_id
book_id