[postgis-users] how to write the sql if i want to find a geometry's d-distance neighbors?

[Francis Markham]

Hi Sunpeng,

Definitely use ST_DWithin.

-Francis

On 13 September 2010 06:51, sunpeng <bluevaley at gmail.com> wrote:

> Hi,
>  I've the following table,and has created the index on uid and location;
> CREATE TABLE points
> (
>   location geometry, //assume it's a 2-dimension point
>   uid integer
> )
>
> Now, I've a point P with uid= 12345, and want to find the neighbors which
> are within 20, how to write the sql?Is this right?
> select st_astext(location)
> from points a, points b
> where b.rid = 12345 and ST_DWithin(a.the_geom, b.the_geom, 20)
>
> or use st_buffer? which one is more efficient ?
>
> Thanks!
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