users, roles, groups

• The database contains three tables: user, role, and group.
• These tables form a chain:

- A user (parent table) can have one or more roles (child table).

- Each role points to the user and to a specific group (the role table has multiple foreign keys)

- Each group defines an access_code that represents a permission scope.

• When User A logs in:

- The system looks up all roles assigned to User A.

- User A has roles in three groups: Group B, Group C, and Group D.

- Each of these groups provides its own access_code:

- Group B → code B

- Group C → code C

- Group D → code D

• The login process collects these access codes.
• The three codes are stored as items in the session array:

- `$_SESSION['xs'] = [A, B, C]`

• Conceptually:

- A user inherits permissions from all groups linked by role.

- The session becomes the active permission set for that user.

- The system only needs the codes in `xs` to determine what the user can access.

make relationships

ALTER TABLE role

ADD CONSTRAINT fk_role_user

FOREIGN KEY (user_id)

REFERENCES user(id)

ON DELETE CASCADE

ON UPDATE CASCADE;