SDO_GEOM.SDO

Format

SDO_GEOM.SDO_UNION(     
  geom1 IN SDO_GEOMETRY,      
  dim1  IN SDO_DIM_ARRAY,      
  geom2 IN SDO_GEOMETRY,      
  dim2  IN SDO_DIM_ARRAY       
) RETURN SDO_GEOMETRY;

or

SDO_GEOM.SDO_UNION(     
  geom1 IN SDO_GEOMETRY,      
  geom2 IN SDO_GEOMETRY,      
  tol   IN NUMBER       
) RETURN SDO_GEOMETRY;

Description

Returns a geometry object that is the topological union (OR operation) of two geometry objects.

Parameters

geom1: Geometry object.
dim1: Dimensional information array corresponding to geom1, usually selected from one of the xxx_SDO_GEOM_METADATA views (described in Geometry Metadata Views).
geom2: Geometry object.
dim2: Dimensional information array corresponding to geom2, usually selected from one of the xxx_SDO_GEOM_METADATA views (described in Geometry Metadata Views).
tol: Tolerance value (see Tolerance).

Usage Notes

In Figure 25-4, the shaded area represents the polygon returned when SDO_UNION is used with a square (geom1) and another polygon (geom2).

Figure 25-4 SDO_GEOM.SDO_UNION

Description of "Figure 25-4 SDO_GEOM.SDO_UNION"

If it is sufficient to append one geometry to another geometry without performing a topological union operation, and if both geometries are disjoint, using the SDO_UTIL.APPEND function (described in SDO_LRS Package (Linear Referencing System)) is faster than using the SDO_UNION function.

An exception is raised if geom1 and geom2 are based on different coordinate systems.

Examples

The following example returns a geometry object that is the topological union (OR operation) of cola_a and cola_c. (The example uses the definitions and data from Simple Example: Inserting_ Indexing_ and Querying Spatial Data.)

-- Return the topological union of two geometries.
SELECT SDO_GEOM.SDO_UNION(c_a.shape, m.diminfo, c_c.shape, m.diminfo) 
  FROM cola_markets c_a, cola_markets c_c, user_sdo_geom_metadata m 
  WHERE m.table_name = 'COLA_MARKETS' AND m.column_name = 'SHAPE' 
  AND c_a.name = 'cola_a' AND c_c.name = 'cola_c';

SDO_GEOM.SDO_UNION(C_A.SHAPE,M.DIMINFO,C_C.SHAPE,M.DIMINFO)(SDO_GTYPE, SDO_SRID,
--------------------------------------------------------------------------------
SDO_GEOMETRY(2003, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARR
AY(5, 5, 5, 7, 1, 7, 1, 1, 5, 1, 5, 3, 6, 3, 6, 5, 5, 5))

Note that in the returned polygon, the SDO_ORDINATE_ARRAY starts and ends at the same point (5, 5).