Fwd: how to write the sql if i want to find a geometry's d-distance neighbors?

[sunpeng <bluevaley@xxxxxxxxx>]

I can't mail it to: postgis-users@xxxxxxxxxxxxxxxxxxxxxxx
so could administrator forword this mail to them? thanks!

From: sunpeng <bluevaley@xxxxxxxxx>
Date: 2010/9/12
Subject: how to write the sql if i want to find a geometry's d-distance neighbors?
To: postgis-users@xxxxxxxxxxxxxxxxxxxxxxx


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!