Question

I’m creating a database users. I want to let users to choose notifications they want to receive by email.

Now I have the next columns in table users (boolean type):

• notification_comment_photo.

• notification_comment_comment.

• notification_vote_photo.

• notification_vote_comment.

• notification_pm.

• notification_followed.

• notification_news.

What do you think, should I normalise table users and create another table notifications, considering that this table would have one-to-one relationship to table users?

Also I have the same problem with social links (twitter, facebook, google+, etc). Is it better to make a separate table links?

upd. Thanks all, I’ll add the separate tables.

Answer 1

It’s hard to answer your question, because you’re not telling us what problem you’re trying to solve.

One issue with your current design is that it requires a schema change for every new type of notification you want to store – if you want to notify users when they’ve been un_followed, you have to add a column to your users table.

I’d consider a schema like:

TABLE: users
------------------
ID
...

TABLE: notification_types
----------------------
ID
Description

TABLE: user_notifcation_subscriptions
-----------------------------------------
user_id
notification_type_id
subscribed (bool)

You could leave the “subscribed” column out of user_notification_subscriptions and decide that any record linking a user to a notification type means they have subscribed.

This design allows you to add new subscription types without changing the schema. I believe it’s similar to the design @Daniel suggests, but he doesn’t include the notification_type table, relying instead on name-value pairs. I’m not a fan of this – it can lead to silly, hard-to-find bugs when typos slip into the TYPE column.