Question

I have a set of checkboxes that an Admin can tick to give users privleges. In my case, the Admin can click these checkboxes: Image on ImageShack. These checkboxes will allow users to view data for those countries/cities.

http://img205.imageshack.us/img205/4170/screenshotao.png

I am trying to rack my brains to do the folowing:

1) How to best insert this permissions into my database
2) How to later work out what permissions each user is allowed

At the moment, I am thinking of just adding lots of columns for each checkbox into my db and put a 1 or 0 there. Then check these using lots of if functions!! This is going to be a time waster when coding.

Is there anything else I can do? I appreciate any help!

Answer 1

You need the SET data type. A SET is more or less a bit field where each bit has a name:

ALTER TABLE user ADD COLUMN permissions SET(
    'States',
    'Cities',
    'Africa',
    'Asia',
    'Australia',
    'Europe',
    ...
);

Selecting users that can view data for asia:

SELECT * FROM user WHERE FIND_IN_SET('Asia',permissions) > 0;

Or selecting all users that can view Asia and Europe but not Africa:

SELECT * FROM user WHERE permissions & 40 = 40 AND !(permissions & 4)

I would further define these constants in PHP, then your code should be quite readable:

define('PERMISSION_STATES', 1);
define('PERMISSION_CITIES', 2);
define('PERMISSION_AFRICA', 4);
define('PERMISSION_ASIA', 8);
define('PERMISSION_AUSTRALIA', 16);
define('PERMISSION_EUROPE', 32);
# ...

# Check if user can view data for Africa
if ($user['permissions'] & PERMISSION_AFRICA) {
    # ...

# Check if user can Asia and Europe but not Africa
if ($user['permissions'] & PERMISSION_ASIA
    && $user['permissions'] & PERMISSION_EUROPE
    && !($user['permissions'] & PERMISSION_AFRICA)) {
    # ...