Question

I want to create an “users” table which include a “email address” and/or “userName” unique field, should I also add an “id” int usigned auto_increment to be the primary key or not?

I’m asking because I’ve seen some textbook examples using an “id” field in such a table with another unique field.

Answer 1

Yes, it’s best practice.

1. You will use it as foreign key in other tables.
2. You want the key to remain unique (you might want to change username)
3. You want the key to be indexed, index will be much smaller for numeric type, than for varchar.