Tom Janssens wrote:
> My problem is that I should be able to let the Database System (Postgresql)
> generate its own primairy keys (from the rest of the data).
> workplace_ID, name, street, nr, zipcode, city, country
>
> workplace_ID is the primairy key of that table. Some other tables have a
> foreign key refering to it. As a primairy key this ID is of course unique.
> My Question is: How can I see which values (of the primairy key) are already
> taken, and which is available for new data.
Other than with SELECT?
If it's not too late, I'd make workplace_ID into a serial and let
PostgreSQL generate the values for you.
If it is too late, and workplace_id is text you could try appending
nextval(some_seq) to the end of it - that would guarantee uniqueness.
- Richardh
