ST_MPolyFromText function

The ST_MPolyFromText function takes a well-known text representation of a multipolygon and, optionally, a spatial reference system identifier as input parameters and returns the corresponding multipolygon.

If the given well-known text representation is null, then null is returned.

The recommended function for achieving the same result is the ST_MultiPolygon function. It is recommended because of its flexibility: ST_MultiPolygon takes additional forms of input as well as the well-known text representation.

Syntax

Parameters

wkt

A value of type CLOB(2G) that contains the well-known text representation of the resulting multipolygon.

srs_id

A value of type INTEGER that identifies the spatial reference system for the resulting multipolygon.

If the srs_id parameter is omitted, the spatial reference system with the numeric identifier 0 (zero) is used.

If the specified srs_id does not identify a spatial reference system listed in the catalog view DB2GSE.ST_SPATIAL_REFERENCE_SYSTEMS, then an exception condition is raised (SQLSTATE 38SU1).

Return type

db2gse.ST_MultiPolygon

Example

In the following example, the lines of results have been reformatted for readability. The spacing in your results will vary according to your online display.

This example illustrates how ST_MPolyFromText can be used to create and insert a multipolygon from its well-known text representation. The record that is inserted has ID = 1110, and the geometry is a multipolygon in spatial reference system 1. The multipolygon is in the well-known text representation of a multipolygon. The X and Y coordinates for this geometry are:

Polygon 1: (3, 3) (4, 6) (5, 3) (3, 3)
Polygon 2: (8, 24) (9, 25) (1, 28) (8, 24)
Polygon 3: (13, 33) (7, 36) (1, 40) (10, 43) (13, 33)


SET CURRENT FUNCTION PATH = CURRENT FUNCTION PATH, db2gse
CREATE TABLE sample_mpolys (id INTEGER, geometry ST_MultiPolygon)

INSERT INTO sample_mpolys
  VALUES (1110,
          ST_MPolyFromText ('multipolygon (( (3 3, 4 6, 5 3, 3 3),
                                  (8 24, 9 25, 1 28, 8 24),
                                  (13 33, 7 36, 1 40, 10 43 13 33) ))', 1) )

The following SELECT statement returns the multipolygon that was recorded in the table:


SELECT id, CAST( ST_AsText( geometry ) AS VARCHAR(350) ) MULTI_POLYGON
  FROM sample_mpolys
  WHERE id = 1110

Results:


ID         MULTI_POLYGON
------- --------------------------------------------------------------------
   1110 MULTIPOLYGON ((( 13.00000000 33.00000000, 10.00000000 43.00000000,
           1.00000000 40.00000000, 7.00000000 36.00000000,
           13.00000000 33.00000000)),
                      (( 8.00000000 24.00000000, 9.00000000 25.00000000,
           1.00000000 28.0000000, 8.00000000 24.00000000)),
                       ( 3.00000000 3.00000000, 5.00000000 3.00000000,
           4.00000000 6.00000000, 3.00000000 3.00000000)))