SDO_TOPO_MAP.GET_NEAREST

Format

SDO_TOPO_MAP.GET_NEAREST_EDGE(     
  topology IN VARCHAR2,      
  topo_map IN VARCHAR2,      
  point    IN SDO_GEOMETRY      
) RETURN NUMBER;

or

SDO_TOPO_MAP.GET_NEAREST_EDGE(     
  topology IN VARCHAR2,      
  topo_map IN VARCHAR2,      
  x        IN NUMBER,      
  y        IN NUMBER      
) RETURN NUMBER;

Description

Returns the edge ID number of the edge that is nearest (closest to) the specified point.

Parameters

topology: Name of the topology that contains the edge and the point, or a null value, as explained in Using GET_xxx Topology Functions. Must not exceed 20 characters.
topo_map: Name of the TopoMap object, or a null value, as explained in Using GET_xxx Topology Functions. (TopoMap objects are explained in TopoMap Objects.)
point: Geometry object specifying the point.
x: X-axis value of the point.
y: Y-axis value of the point.

Usage Notes

The topology or topo_map parameter should specify a valid name, as explained in Using GET_xxx Topology Functions.

The nearest edge is determined from the representation of the topology in the database, using the spatial index. If there are changed, added, or deleted edges in the instance and the database has not been updated to reflect those changes, the result may not reflect the true situation in the TopoMap object cache.

If multiple edges are equally close to the point, any one of the edge ID values is returned. If no edges exist in the topology, this function returns 0 (zero).

This function is equivalent to using the getNearestEdge method of the TopoMap class of the client-side Java API (described in Topology Data Model Java Interface).

Examples

The following example returns the edge ID number of the edge that is closest to the point at (8, 8) in the CITY_DATA_TOPOMAP TopoMap object. (The example refers to definitions and data from Topology Built from Topology Data.)

SELECT SDO_TOPO_MAP.GET_NEAREST_EDGE(null, 'CITY_DATA_TOPOMAP',
  SDO_GEOMETRY(2001, NULL, SDO_POINT_TYPE(8,8,NULL), NULL, NULL))
  FROM DUAL;
 
SDO_TOPO_MAP.GET_NEAREST_EDGE(NULL,'CITY_DATA_TOPOMAP',SDO_GEOMETRY(2001,NULL,SD
--------------------------------------------------------------------------------
                                                                              22