Question

I’ve got my tables posts and user_unread_posts.
In posts, all the posts of a forum are saved, and in user_unread_posts all posts are saved which are read by a user.

user_undread_postslooks like this:

id   uid   pid

Now I want to allow users to open a random post which they haven’t read. I’ve tried something like

SELECT * FROM posts
LEFT JOIN user_unread_posts uup
ON uup.pid=posts.id
WHERE uup.uid<>1
ORDER BY RAND()
LIMIT 1

(Whilst 1 is a placeholder UID)

But it doesn’t work, like it should work, it return posts too, which are read… How can I fix that?

Answer 1

SELECT  *
FROM    posts
WHERE   id NOT IN
        (
        SELECT  pid
        FROM    user_unread_posts uup
        WHERE   uid = $myuserid
        )
ORDER BY
        RAND()
LIMIT 1