function get_category($uid) {
    $query = $this->db->query("SELECT * FROM " . DB_TABLEPRE . "user_category WHERE uid=$uid");
    $categorylist = array();
    while ($category = $this->db->fetch_array($query)) {
        $category['categoryname'] = $this->base->category[$category['cid']]['name'];
        $categorylist[] = $category;
    }
    return $categorylist;
}