Oracle table management : add, delete

[Palmero]

Hi all,

I am developping with Visual Basic 6.0 attacking an Oracle 8 database.
I have a table (code primary key, description).

I want :
- to add a given code if the code does not exist.
- to delete a given code if the code exists.

If you have a sample code managing the evolution of such a table, your help will be appreciated.

Thanks in advance.

Palmero.