Laravel加入并显示子类别

Question

I try to build a forum-like query with joins, but without success so far.

What I have so far is:

$categories = DB::table('categories')
            ->join('forums', function($forums) {
                $forums->on('categories.id', '=', 'forums.categoryid');
            })
            ->leftJoin('topics', function($topics) {
                $topics->on('forums.id', '=', 'topics.forumid');
            })
            ->get();

In database i have two forums records and one category record, but this query shows two same categories but 2 different forums.

Example:

Array
(
    [0] => stdClass Object
        (
            [id] => 1
            [title] => Üldine
            [description] => Kõik üldine siia
            [categoryid] => 1
            [forum_name] => Informatsioon
            [forum_description] => Kõik seoses kommuuniga...
            [forumid] => 1
            [topic_name] => Test Topic 1
            [topic_description] => Test topic description
        )

    [1] => stdClass Object
        (
            [id] => 
            [title] => Üldine
            [description] => Kõik üldine siia
            [categoryid] => 1
            [forum_name] => Informatsioon 2
            [forum_description] => Info 2 test
            [forumid] => 
            [topic_name] => 
            [topic_description] => 
        )

)

Is it even possible to do that with joins?

Best regards!