[postgis-users] intersection/within queries - newbie basic spatial queries

[Josh Livni]

Craigie,

Not 100% sure I parsed your question right.  It's possible others may 
also be confused.  You say 'all the polys in sec_catch fall within a 
single record of prim_catch' .. are you then wondering which polygon of 
sec_1 it is that they all fall within?

Or maybe, what you're trying to accomplish is to get, for each polygon 
in the prim_catch table, a list of all polygons from sec_catch that are 
inside that prim_catch polygon.... ?

On the other hand, I may be misunderstanding something obvious, in which 
case I am sure others will be able to assist without further translation.

Cheers,

  -Josh

Craigie Dirk wrote:
>
> I am a new user and trying to perform some basic spatial queries using 
> within/intersect/union etc.
>
>  
>
> I have 2 x polygon files :
>
>  
>
> Prim_catch (19 x records)
>
> Sec_catch (attribute secondary = text field name of catchment)
>
>  
>
> All the polys in sec_catch fall within a single record (polygon) of 
> prim_catch  
>
> The query I am using (see below) needs some kind of loop or temporary 
> table as it returns a true/false and not a list of the records = true.
>
> ------------
>
> SELECT secondary FROM sec_catch 
>
> WHERE WITHIN((select the_geom from sec_catch),(select the_geom from  
> prim_catch))
>
> -----------
>
>  
>
> Any help, sample will be appreciated
>
>  
>
> Thanks,
>
>  
>
>  
>
> Dirk Craigie
>
>  
>
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