Remove duplicate form select result - mysql

Question

#edited
Ok. I will delete all role permissions and add them again.
Is it possible to combine all 4 queries into one?
I am creating a permission system.
Assumptions:
Each user can have more than one role
Each role can have more than one permission
Permissions can also be assigned directly to the user (they have a higher priority than permissions for roles)
The priority of permissions is:
role permission
denial of role
user permission
denied to user
Denying the user has the highest priority
The matter in PHP is quite simple:
I create an array with all permissions
I am getting permissions for a role (order by access)
I assign access, if it's denied, I overwrite access with denied
I do the same for user permissions
I assign access, if it's denied, I overwrite access with denied
This way I have the whole array with permissions for a specific user, e.g. $ user['permission']['delete_post'] // output: false || true
I need to do permission inspection now. This means which user has access to e.g. 'delete_post'
I have this database scructure:
Here fiddle with database: DB fiddle
I have problem with first query:
**Query #1**
=============================================
List of all roles related to permission with id 3 */
SELECT DISTINCT role_id, access, permission_id FROM role_permissions WHERE permission_id=3 ORDER BY role_id, access DESC;
| role_id | access | permission_id |
| ------- | ------ | ------------- |
| 5 | 0 | 3 |
| 8 | 1 | 3 |
| 10 | 1 | 3 |
| 10 | 0 | 3 |
As expected I should get
| role_id | access | permission_id |
| ------- | ------ | ------------- |
| 8 | 1 | 3 |
I cant add WHERE permission_id=3 AND access=1, because i getting result: role_id=8 and role_id=10, but role_id=10 doesn't really have access.

Answer 1

One way is to do all appropriate joins between various tables based on their relationships, and then do aggregation based filtering using GROUP BY with HAVING clause.
Following query will give you all the users who has access allowed for a given permission id (more explanation in comments inside the query below - there may be requirement of more fiddling with the logic; check and comment if needed):
Query - View on DB Fiddle
SELECT
u.user_id,
u.name
FROM users AS u
-- Left Join to get access (if defined for input permission id)
LEFT JOIN user_permissions AS up
ON up.user_id = u.user_id
AND up.permission_id = 3
-- Join to Roles; assuming every user has atleast one role
-- Change this to LEFT JOIN if it is possible that user can have NO role
JOIN user_roles AS ur
ON ur.user_id = u.user_id
-- Left Join to get access defined for input permission id for roles
LEFT JOIN role_permissions AS rp
ON rp.role_id = ur.role_id
AND rp.permission_id = 3
GROUP BY u.user_id, u.name
HAVING
-- first priority if user specific access allowed
-- if data is sane then up.access will have same value
-- across all rows in a group for user
MAX(up.access) = 1
OR
-- second priority is not have a single role with
-- denied permission AND
-- atleast one role exists with allowed permission
( NOT SUM(rp.access = 0)
AND
SUM(rp.access = 1)
);
Result
| user_id | name |
| ------- | ---------------- |
| 4 | Cyrus Gomez |
| 7 | MacKensie Morton |
| 13 | Nadine Taylor |
| 15 | Ezekiel Bonner |
| 17 | Ciaran Turner |
| 35 | Olga Dominguez |
| 38 | Lucas Pierce |

Answer 2

You can add a WHERE condition as below-
SELECT DISTINCT role_id, access, permission_id
FROM role_permissions
WHERE permission_id=3
AND role_id NOT IN (
SELECT DISTINCT role_id
FROM role_permissions
WHERE access = 0
AND permission_id=3 -- New condition added
)
ORDER BY role_id, access DESC;