[postgis-users] Creating an ID field in a view

[Mark Cave-Ayland]

On Thu, 2007-03-29 at 17:15 +0200, Jose Gomez-Dans wrote:
> Hi!
> Beginner's warning :)
> 
> I am tryingn to create a view which is the result of I  a
> GeometryUnion betwen polygon tables. Hopefully, I will get a lot of
> split entries. If I then want to represent the results using QGIS (and
> for my own purposes), I need to create an unique field per feature. Is
> there some function which will add this field and populate it
> accordingly? I am not interested in its value, only in the fact that
> it has to be unique for each feature in the view.
> 
> Can anyone shed any light? I have gone through the documentation, but
> I haven't actually seen anything which seems related.
> 
> Many thanks,
> jose


Hi Jose,

If you don't care if the value changes each time you run the query,
simply create a sequence and reference it in your SELECT, e.g.

CREATE SEQUENCE foo CYCLE;
SELECT nextval('foo') AS id, the_geom FROM .... etc.


Kind regards,

Mark.