[postgis-users] Re: INSERT Commands

[Markus Schaber]

Hi, Gerhard,

gerhard.engel at sbg.ac.at wrote:
> Thanks for explaining the difference between Postgres and PostGIS
> geometries. 
> With respect to POLYGON geometries: how can polygons with a hole be
> created in PostGIS?

You add the inner rings (holes) via (),(),().

POLYGON((0 0, 100 0, 100 100, 0 100, 0 0),(10 10, 10 20, 20 20, 20 10,
10 10))

Be aware that rings may not intersect each other, you might want to look
in the OpenGIS Spec for the exact definitions. And the isvalid()
function can be used to check your geometry for validity.

Also see my mail from 10/25/05 14:10, Subject: Re: [postgis-users]
GeometryN.

Markus