User System - Multiple Roles in MySQL Database - mysql

Question

So I am in the process of attempting to create a basic user system and within this system I want users to be able to have multiple roles.
Say for example I have the roles as follows: Administrator, Events Organiser, Donator
What is the best way to assign these multiple roles to a user and then check if they have any of these roles for showing certain permissions.
If it was only one role per person then it wouldn't be a problem as I'd just assign say Administrator = 10, Organiser = 5 and Donator = 1 and then do an if statement to check if the MySQL data is equal to any of those three numbers.
I can't imagine there is a way to add a MySQL Field and fill it with say "Administrator,Donator" and therefore that user would have both of those roles?
Is it just a case of I would need to create 3 separate fields and put a 0 or a 1 in those fields and check each one separately?

Answer 1

Use multiple tables and join them:
User
--------------
id name
1 test
Role
--------------
id name
1 Donator
2 Organizer
3 Administrator
User_Role
--------------
id user_id role_id
1 1 1
2 1 3
SELECT * FROM User u
LEFT JOIN User_Role ur ON u.id = ur.user_id
LEFT JOIN Role r ON ur.role_id = r.id
WHERE r.name = "Administrator";
The query is easier if you know you only have 3 roles and they are easy to remember.
SELECT * FROM User u LEFT JOIN User_Role ur ON u.id = ur.user_id WHERE ur.role_id = 3;

Answer 2

You will have a roles, users and users_roles tables:
The roles table will hold the various roles your users can have. In my example data I've declared Administrator and Donator roles.
roles
id unsigned int(P)
description varchar(15)
+----+---------------+
| id | description |
+----+---------------+
| 1 | Administrator |
| 2 | Donator |
| .. | ............. |
+----+---------------+
And of course you'll have to store information about your users.
users
id unsigned int(P)
username varchar(32)
password varbinary(255)
etc.
+----+----------+----------+-----+
| id | username | password | ... |
+----+----------+----------+-----+
| 1 | bob | ******** | ... |
| 2 | mary | ******** | ... |
| .. | ........ | ........ | ... |
+----+----------+----------+-----+
Finally you'll tie the two together in the users_roles table. In my example data you can see that bob is a Donator and mary is both an Administrator and a Donator. The user_id and role_id are both foreign keys to their respective tables and together they form the primary key for this table.
users_roles
user_id unsigned int(F user.id)\_(P)
role_id unsigned int(F role.id)/
+----+---------+---------+
| id | user_id | role_id |
+----+---------+---------+
| 1 | 1 | 2 |
| 2 | 2 | 1 |
| 3 | 2 | 2 |
| .. | ....... | ....... |
+----+---------+---------+
This way a user can have an unlimited number of roles.

Answer 3

If you don't want to create two new table for such small thing.
You can utilize MySQL built in SET data type or you can store comma separated role in varchar and do query operation using FIND_IN_SET()
Eg.
SELECT * FROM user WHERE FIND_IN_SET('admin', role)>0;
+----+----------+----------+----------------+
| id | username | password | role (varchar) |
+----+----------+----------+-----------------+
| 1 | bob | ******** | admin |
| 2 | mary | ******** | admin,role1 |
| .. | ........ | ........ | role1,role2 |
+----+----------+----------+-----------------+