Пример кода

<?php


class Posts {

    private $postUserId;
    private $postsArr;
    private $userPostsArr;
    private $postInfoArr;


    public function get($id = false, $limit = false) {
        if ($id) {
            $this->postUserId = $id;
            $this->userPostsArr = $this->getUserPosts($id, $limit);
            $userPostIdsStr = implodeIds($this->userPostsArr, 'post_id');
            $this->postInfoArr = $this->getPostsInfo($userPostIdsStr);
            $this->postsArr = $this->postCombine();

        } else {
            $this->userPostsArr = $this->getPostsInfo();
        }
        return $this->postsArr;
    }

    private function getUserPosts($id, $limit = false) {
        $select = DB::select('staff_employee_posts');
        $select->whereEquals('id_emp', $id);
        if ($limit) {
            $select->limit($limit);
        }
        return $select->fetchAll();
    }

    private function getPostsInfo($postIdsStr = false) {
        $select = DB::select('staff_posts');
            if ($postIdsStr) {
                $select->whereIn('id', $postIdsStr);
            }
            return $select->fetchAll();
    }

    private function postCombine() {
        $postArrById = arrayToAssoc($this->postInfoArr, 'id');
        if ($this->userPostsArr) {
            foreach ($this->userPostsArr as $post) {
                $postsArr[] = new Post(
                    $post += (array_key_exists($post['post_id'], $postArrById)) ? $postArrById[$post['post_id']] : []
                );
            }
        } else {
            $postsArr[] = new Post(['name' => 'Не заполнено']);
        }

        return $postsArr;
    }

}