> First rule of database design: Your unique IDs should not have a real-world meaning. I see a lot of comments conflating a unique ID with a unique column. It'

> First rule of database design: Your unique IDs should not have a real-world meaning. I see a lot of comments conflating a unique ID with a unique column. It's OK for you to have a unique contraint on something like an email column. But you wouldn't use the email column as the primary key.