Question

I have 5 tables in MySQL, but i believe this is a SQL problem

USERS

USER_INFO

USER_RIGHTS

101 = read right

102 = write right

GROUPS

POSTS

Now i want to select for user 2 for example, all posts made by any user where user 2 has the read right 101 in that group

For example i have 3 post

post 1 posted in group 1
post 2 posted in group 1
post 3 posted in group 2
post 4 posted in group 1

and

WHERE user2 has 101 right in group 1 ==> SHOW post1 2 3

or

WHERE user2 has 101 right in group 2 ==> SHOW post2

or

WHERE user2 has 101 right in both group 1 and group 2 ==> SHOW post2

What i have so far is

SELECT * FROM posts
INNER
    JOIN user_info
    ON posts.posted_by = user_info.user_id  
INNER
    JOIN groups
    ON posts.posted_in = groups.group_id
INNER
    JOIN user_rights
    ON user_rights.user_id = user_info.user_id
WHERE user_rights.right = '101' AND user_info.user_id = ".$UserId." ORDER BY id DESC;

This piece of code returns me all posts 2 times.

Answer 1

Im pretty much convinced this

select * from posts 
inner join 
(select group from user_rights where right = 101 and user_id = 1) as rights
on posts.posted_in = rights.group

would work in SQL server (dont have one here to check the syntax).

On one side im selected all the groupswhere user with id 1 has a read permssion

On the other i select the posts.

All is left is the inner join between them.