public function getColumnMeta($colnum=0)
    {
        if (!$this->_stmt) {
            return null;
        }
        $name = \oci_field_name($this->_stmt, $colnum+1);
        $len  = \oci_field_size($this->_stmt, $colnum+1);
        $prec = \oci_field_scale($this->_stmt, $colnum+1);
        $type = \oci_field_type($this->_stmt, $colnum+1);
        return array("name"=>$name, "len"=>$len, "precision"=>$prec, "driver:decl_type"=>$type);
    }