Question

Here are two tables I designed for managing user accounts.

create table if not exists users (
  id int unsigned not null auto_increment,
  username varchar(100) not null,
  password binary(60) not null,
  first_name varchar(100) not null,
  last_name varchar(100) not null,
  role_id int unsigned not null,
  primary key(id),
  unique(username)
);

create table if not exists roles (
  id int unsigned not null auto_increment,
  role varchar(100) not null,
  primary key(id),
  unique(role)
);

I think I need to normalize the first table, e.g. splitting the first table into some sort of user_info(first_name, last_name, …) and account (username, password, role_id). The problem I have is that I am very uncertain of why I need to do this, as I can’t really explain why it isn’t in 3NF.

EDIT

A user can only have exactly one role (admin, poweruser, user).

Answer 1

You only need to separate the user information and account information if a user can have multiple accounts or an account can have multiple users. If the user-to-account relationship is always 1-to-1, then you’re normalized as is.

Occasionally it makes sense to separate out columns in a 1-to-1 relationship if the columns in the second table will be used rarely. However, in this case, it seems as though both tables would always be populated, so there’s nothing to be gained by separating those columns.