选择共同关注者

Question

I know this has many questions here but no answer I've found works for me. I'm building a social network and I'm working on the user list page. In my database are two tables, users & followers . The id column in the users table is a foreign key in the followers table whose columns are id , user_id & follower_id . The follower_id is the user id of the user who followed the user_id user.

When showing the list of all users on the social network I want to exclude: 1)The users being followed by the logged_in_user 2)The users following the logged_in_user

When showing the list of all users I also want to prioritize any mutual followers to be displayed first.

This are my current queries ( $userid refers to the logged_in_user and $start is an integer sent when the user loads more users)

<?

//list of users following the `logged_in_user`
$followers = $db->query(
        'SELECT followers.id, followers.user_id, followers.follower_id, users.id, users.username, users.profileimg 
        FROM followers, users 
        WHERE followers.user_id=:userid 
        AND followers.follower_id=users.id 
        LIMIT 8 OFFSET '.$start.';', array(':userid'=>$userid));

//list of users being followed by the `logged_in_user`
$following = $db->query(
        'SELECT followers.id, followers.user_id, followers.follower_id, users.id, users.username, users.profileimg 
        FROM followers, users 
        WHERE followers.follower_id=:userid 
        AND followers.user_id=users.id 
        LIMIT 8 OFFSET '.$start.';', array(':userid'=>$userid));

//list of all users: here I excluded the `logged_in_user`
$users = $db->query(
        'SELECT users.id, users.username, users.profileimg, users.gender, users.last_seen 
        FROM users 
        WHERE users.id!=:userid 
        LIMIT 8 OFFSET '.$start.';', array(':userid'=>$userid));

?>

Could anyone help me tie these three queries together to get the desired result: A list of all users who are following/being followed by the users who are following/being followed by the logged_in_user ie mutual followers. Thanks.

UPDATE I have found some code to help me remove the users following/being followed by logged_in_user

 <? //remove followers from list of users foreach ($followers as $fr) { foreach($users as $elementKey => $element) { foreach($element as $valueKey => $value) { if($valueKey == 'username' && $value == $fr['username']){ //delete this particular object from the $users unset($users[$elementKey]); } } } } //remove users following logged_in_user from list of users foreach ($following as $fg) { foreach($users as $elementKey => $element) { foreach($element as $valueKey => $value) { if($valueKey == 'username' && $value == $fg['username']){ //delete this particular object from the $users unset($users[$elementKey]); } } } } ?> 

All I need now is to fetch all users whose id matches the follower_id column in the followers table because their corresponding user_id column will be the mutual followers between the logged_in_user and the users followed/following him/her.

Answer 1

Not an answer. Too long for a comment...

If it was me, I'd start with something like this (including DDLs of same)...

1 Romeo
2 Juliet
3 Benvolio
4 Mercutio
5 Tybalt

user follows
   5       2
   4       1
   4       2
   1       3

...and instead ask, what query can tell us who else is following/being followed by the individuals following/being followed by Romeo.

Answer 2

All I did next after the update above was run another query that fetched the desired users.

 <? foreach ($users as $ur) { $user_id = $ur['id']; $mutual[]= $db->query('SELECT followers.id, followers.user_id, followers.follower_id, users.id, users.username, users.profileimg FROM followers, users WHERE followers.follower_id=:userid AND followers.user_id=users.id LIMIT 100 OFFSET '.$start.';', array(':userid'=>$user_id)); } echo json_encode($mutual); ?>