Проблема с выводом компонента статей на главную

 
DATABASE ERROR:
 
SELECT id, title, NSLevel, seolink, url
                FROM cms_category
                WHERE NSLeft <=  AND NSRight >=  AND parent_id > 0
                ORDER BY NSLeft
 
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND NSRight >= AND parent_id > 0 ORDER BY NSLeft' at line 3

    public function getCategoryPath($left_key, $right_key) {
 
        $path = array();
 
        $sql = "SELECT id, title, NSLevel, seolink, url
                FROM cms_category
                WHERE NSLeft <= $left_key AND NSRight >= $right_key AND parent_id > 0
                ORDER BY NSLeft";
 
        $result = $this->inDB->query($sql);
 
        if (!$this->inDB->num_rows($result)) { return false; }
 
        while($cat = $this->inDB->fetch_assoc($result)){
            $path[] = $cat;
        }
 
        return $path;
 
    }