Question

I have 4 tables in MySQL

USERS

USER_INFO

USER_RIGHTS

101 = read right

102 = write right

103 = delete right

GROUPS

Now when i want to select all users using INNER JOIN i do something like

SELECT users.id, user_info.first_name, user_info.last_name, user_rights.right
    FROM `users`
INNER 
    JOIN user_info 
    ON users.id = user_info.user_id
ORDER BY user_info.first_name;

and i get 2 users.

I want to make another INNER JOIN that selects members that have rights in group 1 for example, but my code dosen’t work …

SELECT users.id, user_info.first_name, user_info.last_name, user_rights.right
    FROM `users`
INNER 
    JOIN user_info 
    ON users.id = user_info.user_id
INNER 
    JOIN user_rights 
    ON user_rights.rights = '101' 
ORDER BY user_info.first_name;

The idea is to select what members has the READ right in a certain group. Hope i make myself clear.

Answer 1

use Left Join with User_Rights to get all users and rights

SELECT users.id, 
       user_info.first_name, 
       user_info.last_name, 
       user_rights.right 
FROM   users 
       INNER JOIN user_info 
         ON users.id = user_info.user_id 
       LEFT JOIN user_rights 
         ON user_rights.user_id = users.id 
            AND user_rights.right = '101' 
       LEFT JOIN GROUPS 
         ON user_rights.group = GROUPS.group 
            AND groups.group_name = 'Human Resources' 
ORDER  BY user_info.first_name;