Many database rows vs one comma separated values row

Question

I\'m creating a table for allowing website users to become friends. I\'m trying to determine which is the best table design to store and return a user\'s friends. The goal i

Answer 1

Breaking from 1st normal form is usually not desirable because

1. Easy to Orpahned ids
2. Easy to insert invalid data types
3. Updates can require full table scans
4. Increases concurrency issues
5. No way to create the key (user_id, friend_id)