Storing flags in a DB

Question

In my application, I'd like the user to select his working days. then store them in the database. Of course my application will process the users' data like: Is today a working day for a specific user, who are the users that should work today , ... etc.

My question is, what is the best practice for doing this? should I use:

1. Bitmasking field in the users table
2. Many to many relationships tables by creating table for days, users and days_users. Thank you in advance.

Answer 1

I would say that bit mask fields are a relational anti-pattern.

A field should have a single meaningful value, otherwise you end up with querying issues - parsing the field every time you need to query using it.

Such a field also requires extra documentation, as the values it stores are not self describing.

Answer 2

Bitmasking field is a bit more cryptic in nature and you need to create something else to interpret what you store in the bitmask.

The second approach is a lot more transparent and easily understandable and it's a bit more flexible if you need to add more values. With the bitmask, you again need to redo your bitmap decoder each time you add a value which can be a maintainance nightmare compared to the relational approach.