Extract first coordinate

Question

I have a table with polygon geometries in. I want to extract the first coordinate of all the geometries. I can get them all using GETVERTICES but I only want the first one.
Any help gratefully received.
Ivan

Answer 1

Hi Ivan,
I use following function:
FUNCTION FNC_GET_POINT_2D (
     P_GEOM MDSYS.SDO_GEOMETRY
          ,P_POINT_NR PLS_INTEGER DEFAULT 1 -- which point?
          ) RETURN MDSYS.SDO_GEOMETRY
     IS
     lg_geom MDSYS.SDO_GEOMETRY; -- geometry
     ln_dim PLS_INTEGER; -- dimensions
     ln_p PLS_INTEGER; -- index (for array)
     px NUMBER;
     py NUMBER;     
     BEGIN
     -- Number of dimensions
     ln_dim := SUBSTR(P_GEOM.SDO_GTYPE,1,1);
-- exists the point?
     IF P_POINT_NR < 1 OR P_POINT_NR > P_GEOM.SDO_ORDINATES.COUNT()/ln_dim THEN
     RETURN NULL;
     END IF;
     -- index in the ordinate array
     ln_p := (P_POINT_NR-1)*ln_dim+1;
     -- extract the x and y values
     px := P_GEOM.SDO_ORDINATES(ln_p);
     py := P_GEOM.SDO_ORDINATES(ln_p+1);     
     --return the point...
     RETURN MDSYS.SDO_GEOMETRY(
     2001,
          P_GEOM.SDO_SRID,
          MDSYS.SDO_POINT_TYPE(px,py,NULL),
          NULL,NULL);
     END FNC_GET_POINT_2D
then:
SELECT
FNC_GET_POINT_2D(A.GEOMETRY,1).SDO_POINT.X,
FNC_GET_POINT_2D(A.GEOMETRY,1).SDO_POINT.Y,
FNC_GET_POINT_2D(A.GEOMETRY,1).SDO_POINT.Z
FROM
<TABLE> A
returns x,y,z... (first point)
Hope that helps...