Hi Sunpeng, Definitely use ST_DWithin.
-Francis On 13 September 2010 06:51, sunpeng <blueva...@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! > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > >
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