protected function prepareSelect($select, $from, $where='', $group='', $having='', $order='', $limit=''){     
        $sql= "SELECT " . $select;
        $sql.= " FROM " . $from;
        if($where != '' && $where != NULL){$sql.= " WHERE " . $where;}        
        $sql.= $group;
        if($having != '' && $having != NULL){$sql.= " HAVING " . $having;}
        $sql.= $order;
        $sql.= $limit;
        //Preparo la consulta y la retorno
        return $this->connection->prepare($sql);
    }