[postgis-users] Existance of a point on an edge

[Simon Greener]

> From a multilinestring (road path  which is an edge) how can I find whether a
> particular point exist?
> Both the point and the road paths are in geometry format. I need to find in
> which edge, a particular point exists(e.g. current user position).

Is this like what you are after?

drop table roadcl;
create table roadcl ( 
  gid serial );
SELECT AddGeometryColumn('public', 'roadcl', 'geom', 28355, 'LINESTRING', 2);

insert into roadcl (geom)
select geom
from (select ST_SetSRID(ST_GeomFromText('LINESTRING( 1 0, 1 5, 1 11 )'),28355) as geom
      union all
      select ST_SetSRID(ST_GeomFromText('LINESTRING( 10 0, 10 5, 10 11 )'),28355) as geom
      union all
      select ST_SetSRID(ST_GeomFromText('LINESTRING( 0 1, 5 1, 11 1 )'),28355) as geom
      union all
      select ST_SetSRID(ST_GeomFromText('LINESTRING( 0 10, 5 10, 11 10 )'),28355) as geom) as g;

drop table mypoint;
create table mypoint ( 
  gid serial );
SELECT AddGeometryColumn('public', 'mypoint', 'geom', 28355, 'POINT', 2);

insert into mypoint (geom)
values (ST_SetSRID(ST_GeomFromText('POINT(1 5)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(1 11)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(1 0)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(10 5)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(10 11)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(10 0)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(5 1)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(11 1)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(0 1)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(5 10)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(11 10)'),28355)),
       (ST_SetSRID(ST_GeomFromText('POINT(0 10)'),28355));

select t1.gid, t2.gid
  from mypoint t1,
       roadcl t2
 where ST_Contains(t2.geom,t1.geom);
  
regards
Simon
-- 
SpatialDB Advice and Design, Solutions Architecture and Programming,
Oracle Database 10g Administrator Certified Associate; Oracle Database 10g SQL Certified Professional
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