As we have seen, often the processing of an object cannot occur unless its SDO_ELEM_INFO
attribute informs an algorithm's decision making. This section will explore the extraction of various elements and subelements from different geometry objects by processing the SDO_ELEM_INFO
array.
The Oracle API from 10gR1 onwards provides the SDO_UTIL.Extract
element extraction function. The function is as follows:
SDO_UTIL.Extract( geometry In SDO_GEOMETRY, element In NUMBER, ring In NUMBER DEFAULT 0 ) Return SDO_GEOMETRY;
Geometry: [Two dimensional] geometry from which to extract the [Return] geometry.
Element
: Number of the element in the geometry: 1 for the first [...], 2 for the second [...], and so on. Geometries withSDO_GTYPE
values [...] ending in 1, 2, or 3 have one element; [...] ending in 4, 5, 6, or 7 can have more than one element. For example, a [2007] multipolygon […] might...