From foxite forum, as it turned out, there is the "NATIVE" option for sqlcolumns that also does the trick.

=sqlcolumns(iconn, table_name, "NATIVE")

>Hi Yuri,
>
>I've no expirience with Oracle.
>
>>
>>Looks like they both do not work for Oracle. Any other ideas?
>>
>>>>Anyone know a way to retrieve all the column names from a sql table that has more columns than VFP9 or earlier can return in sqlcolumns()?
>>>
>>>John,
>>>
>>>You can use sp_columns system stored procedure or INFORMATION_SCHEMA view

SELECT * FROM pubs.INFORMATION_SCHEMA.COLUMNS
>>>	WHERE table_name = 'authors'
>>>