Laravel - Query Builder - Subquery Joins

You may use the joinSub, leftJoinSub, and rightJoinSub methods to join a query to a subquery. Each of these methods receives three arguments: the subquery, its table alias, and a closure that defines the related columns. In this example, we will retrieve a collection of users where each user record also contains the created_at timestamp of the user's most recently published blog post:

    $latestPosts = DB::table('posts')
                       ->select('user_id', DB::raw('MAX(created_at) as last_post_created_at'))
                       ->where('is_published', true)
    $users = DB::table('users')
            ->joinSub($latestPosts, 'latest_posts', function ($join) {
                $join->on('', '=', 'latest_posts.user_id');