Permissions structure

[8utt]

I have a project I'm trying to set up but I'm not sure how to go about it.


I have a list of projects in a table ( called projects )

What I want to do is add permissions to this either by adding a field on the projects table or the users table.

I want to have the following scenrios,

User A can see every project except project 1
User B can only see project 2
User C can see everything

I was thinking of having 2 columns in the userstable

Allow
Deny

in these fields would be a list of project id's.

any suggestions on the best way of doing this ?

I was thinking of the following way

if allow is empty {
      if deny is emtpy {
                   select * from project
           } else {
                  select * from project where projectid is not in Deny
     } else {
select * from project where projectid is in Allow
}

hopefully that makes sense, can someone think of a better way of doing this ? seems a little messy i think