Question

I have 4 tables… users, friends, articles & article_shares (as in written)

A user can share an article they have created by simply inviting them to read it. What I’m trying find is a list of friends of the article creator (id 63) who have not been invited to share the article yet (id 34).

So, table users:

user_id - name 
10         Dan
11         Doug
12         Chad
13         Ben
63         John

table friends

user_id - friends_id
63        10
63        11
63        12
63        13

table articles

article_id - user_id_creator
34           63

table article_shares

article_id - user_id_sharedWith
34           10
34           11

From the data above I want to return users with id 12 & 13.. chad & ben

Here’s what I’m trying:

select u.name, u.user_id, u.live_prof_pic from users u
join friends f on f.user_id = u.user_id 
join articles a on a.user_id_creator = f.friends_id
join article_shares as on as.articl_id <> a.article_id
where ((f.friends = '63') && (a.article_id = '34'))

It is simply returning 0

Any ideas?

Answer 1

Give this a try,

SELECT  c.friends_ID
FROM    articles a
        INNER JOIN users b
            ON a.user_Id_creator = b.user_ID
        INNER JOIN friends c
            ON b.user_ID = c.user_ID
        LEFT JOIN article_shares d
            a.article_ID = d.article_ID
WHERE   b.user_ID = 63 AND
        a.article_ID = 34 AND
        d.article_ID IS NULL