Find lines with same x,y SDO_Ordinates endpoints

Question

I am trying to find all lines with the same x,y SDO_Ordinates endpoints in an oracle spatial table. The lines have different numbers of vertices. The lines I am trying to find are loops. All lines in the table have GTYPE = 2002.
The logic of the query is something like:
Select * from lines
where SDO_ORDINATES[0] first vertex X coordinate = SDO_ORDINATES[X] last vertex X cooridinate
and SDO_ORDINATES[1] first vertex Y coordinate = SDO_ORDINATES[Y] last vertex Y cooridinate
I am having no success playing around with different combination of the sdo_util.getvertices and sdo_util.getnumvertices funtions.
Thanks,
Mike

Answer 1

Mike,
You need a function like this to do what you want to do:
create or replace function get_vertex(geom sdo_geometry, vertex_type varchar2)
return number is
begin
if (vertex_type = 'FIRST_X') then
return geom.sdo_ordinates(1);
elsif (vertex_type = 'FIRST_Y') then
return geom.sdo_ordinates(2);
elsif (vertex_type = 'LAST_X') then
return geom.sdo_ordinates(geom.sdo_ordinates.count-1);
elsif (vertex_type = 'LAST_Y') then
return geom.sdo_ordinates(geom.sdo_ordinates.count);
else return NULL;
end if;
end;
Use this function to find the first and last vertices and to do the comparisons.
select get_vertex(geom, 'FIRST_X'), get_vertex(geom, 'FIRST_Y'),
get_vertex(geom, 'LAST_X'), get_vertex(geom, 'LAST_Y')
from geom_table;
siva