Question

I need to create a basic database for user authentication. So far, every user has a name, a password and a role. I’ve found this somewhere on the Internet, which looks quite promising:

create table if not exists users (
  id int unsigned not null auto_increment,
  username varchar(100) not null,
  password binary(60) 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)
);

create table if not exists user_roles (
  user_id int unsigned not null,
  role_id int unsigned not null,
  unique(user_id, role_id),
  index(user_id)
);

But… if I would create new users, how would I fill the user_roles table? I have a feeling there is some “automatic way” to do this, but I have totally no idea (being a database noob :-)). How could I somehow connect a user to a role?

Answer 1

You would first populate the roles table. Then, add a user to the users table. Then, taking the ID from the users table, you want to associate it with an ID from the roles table inside of the user_roles table. Like so:

---- Users Table ---------
ID | UserName | Password
 1 | Test     | *****
--------------------------

---- Roles Table ---------
ID | Role
 1 | Test_Role
 2 | Another_Role
--------------------------

---- User Roles Table ---------
UserID | RoleID
     1 |      1
     1 |      2
-------------------------------

This is done for a “Many To Many” relationship. It’s also called “Normalizing” your database.