protected function like($field, $match, $joker='both', $not=FALSE){
        $this->where.= $field . ' ';
        if($not){$this->where.= 'NOT ';}
        $this->where.= 'LIKE ';
        switch ($joker){
            case 'both':
                 $this->where.= "'%$match%' ";
                break;
            case 'after':
                 $this->where.= "'$match%' ";
                break;
            case 'before':
                 $this->where.= "'%$match' ";
                break;
        }
    }