Question

userPosts.value can contain one of two values: 0 or 1.

I am Left Joining userPosts to my Posts table.

I want to get all posts from my Posts table where userPosts.value = 0 as well as all posts that do not have any userPosts.value at all (thus, NULL).

The following only get me posts where value = 0 but no NULL:

SELECT * FROM $wpdb->posts
LEFT JOIN userPosts ON ($wpdb->posts.ID = userPosts.postID)
WHERE userPosts.value != 1
ORDER BY $wpdb->posts.post_date DESC

The following only gets me posts where value = NULL:

SELECT * FROM $wpdb->posts
LEFT JOIN userPosts ON ($wpdb->posts.ID = userPosts.postID)
WHERE userPosts.value IS NULL
ORDER BY $wpdb->posts.post_date DESC

but this yields no results at all:

SELECT * FROM $wpdb->posts
LEFT JOIN userPosts ON ($wpdb->posts.ID = userPosts.postID)
WHERE userPosts.value = 0
AND userPosts.value IS NULL
ORDER BY $wpdb->posts.post_date DESC

and this does get me posts with value = 0 as well as NULL but it repeats all my NULL posts three times!

SELECT * FROM $wpdb->posts
LEFT JOIN userPosts ON ($wpdb->posts.ID = userPosts.postID)
WHERE userPosts.value = 0
OR userPosts.value IS NULL
ORDER BY $wpdb->posts.post_date DESC

So what am I doing wrong?

Answer 1

Try to use parenthasis on OR condition (userContests.value = 0 OR userContests.value IS NULL)

 SELECT * FROM $wpdb->posts
    LEFT JOIN userPosts ON ($wpdb->posts.ID = userPosts.postID)
    WHERE (userContests.value = 0
    OR userContests.value IS NULL)
    ORDER BY $wpdb->posts.post_date DESC