[postgis-users] Postgis for dummies

[Moen, Paul T.]

SELECT DISTINCT ST_X(ST_POINTN(foo.lines,foo.index)) AS x,ST_Y(ST_POINTN(foo.lines,foo.index)) AS y FROM
(select thelines.lines,generate_series(1,thelines.n) AS index FROM
(select polys.geo AS lines, ST_NUMPOINTS(polys.geo) AS n FROM
(SELECT ST_BOUNDARY((ST_DUMP(the_geom)).geom) AS geo FROM "YOURTABLE" WHERE YOURQUERY) AS polys)
AS thelines)
AS foo;


should work for multipolygons and polygons.although there may be an easier way.


Paul Moen


On Nov 6, 2009, at 12:03 PM, Fernando Tong wrote:

I have a dummy question:

i have a POLYGON, how can i get all the polygon's coordinates with a SELECT query?

something like:
select unknown_functions(polygon) from mytable

output:
1 POINT(1 2)
2 POINT(2 2)
3 POINT(3 2)
...

or much better if i get
    X    Y
1  1     2
2  2     2
3  3     2

Thanks a lot.


On Fri, Nov 6, 2009 at 9:19 AM, David Fawcett <david.fawcett at gmail.com<mailto:david.fawcett at gmail.com>> wrote:
I think that another good way to approach it is to have a task/problem
that you want to solve using PostGIS (whether real or made up).  Learn
what you need to about PostGIS to solve that problem and branch out
from there.

David.

On Fri, Nov 6, 2009 at 12:04 AM, Paragon Corporation <lr at pcorp.us<mailto:lr at pcorp.us>> wrote:
> You can also look at some of these - might be helpful
>
> http://www.bostongis.com/PrinterFriendly.aspx?content_name=postgis_tut01
>
> http://workshops.opengeo.org/stack-intro/
>
> This one is a bit dated but probably still useful
> http://2007.foss4g.org/workshops/W-04/
>
> Leo
> ________________________________
> From: postgis-users-bounces at postgis.refractions.net<mailto:postgis-users-bounces at postgis.refractions.net>
> [mailto:postgis-users-bounces at postgis.refractions.net<mailto:postgis-users-bounces at postgis.refractions.net>] On Behalf Of Bob and
> Deb
> Sent: Thursday, November 05, 2009 11:51 PM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] Postgis for dummies
>
> How about the book, "PostGIS in Action" ?   There is even a free chapter
> that might give you enough info to get started.  There is also the Wiki.
>
> -Bob
>
> On Thu, Nov 5, 2009 at 6:34 PM, Jeff Matthews <info at sovereignstates.net<mailto:info at sovereignstates.net>>
> wrote:
>>
>> Need link to tutorial at the “dummy” level.
>>
>>
>>
>> I know a bit about kml, but that’s it.  In looking at postgis, I now see,
>> in the instructions, things like, “To spatially-enable a jump-oriented
>> static sql line pointer,….”   That’s just wayyyy over me.  Where do I go as
>> I newbie in gis to become a pro like you all?
>>
>>
>>
>> Thanks.
>>
>> _______________________________________________
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