That's actually a surprisingly tricky question (to solve efficiently). The approach I have usually used is the counterintuitive one: do a left join on the positive constraint (*is* within 100 meters) and the return the rows that did *not* match the join (and therefore have null unique id values in the resultant).
SELECT tbl_nla.gid FROM tbl_nla LEFT JOIN tbl_rvb ON ST_DWithin(tbl_nla.the_geom, tbl_rvb.the_geom, 100) WHERE tbl_rvb.gid IS NULL; P. On Wed, Jun 9, 2010 at 2:06 PM, G. van Es <[email protected]> wrote: > I have two tables. tbl_nla has points as geometry and tbl_rvb has > multipolygons. > > We want to list all the points of tbl_nla with no objects of tbl_rvb within > 100 metres. > > Can anyone point me in the right direction? > > Thanks, > Ge > > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
