ST_Shape transform group

Use the ST_Shape transform group to transmit data by using the ESRI shape representation.

When binding out a value from the database to a client application, the same function provided by ST_AsShape() is used to convert a geometry to its shape representation. When transferring the shape representation of a geometry to the database, the ST_Geometry(BLOB) function is used implicitly to perform the conversions to an ST_Geometry value. Using the transform group for binding in values causes the geometries to be represented in the spatial reference system with the numeric identifier 0 (zero).

Examples

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

Example 1

The following SQL script shows how the ST_Shape transform group can be used to retrieve a geometry in its shape representation without using the explicit ST_AsShape function.


CREATE TABLE transforms_sample(
   id INTEGER,
   geom db2gse.ST_Geometry)

INSERT
   INTO transforms_sample
   VALUES ( 1, db2gse.ST_Point(20.0, 30.0, 0) )

SET CURRENT DEFAULT TRANSFORM GROUP = ST_Shape

SELECT id, geom
   FROM transforms_sample
   WHERE id = 1

Results:


ID		  GEOM
----   ---------------------------------------------
   1    x'0100000000000000000034400000000000003E40'

Example 2

The following C code shows how to use the ST_Shape transform group to insert geometries using the explicit ST_Geometry function for the host-variable shape_buffer, which is of type BLOB and contains the shape representation of a geometry that is to be inserted.


EXEC SQL BEGIN DECLARE SECTION;
   sqlint32 id = 0;
   SQL TYPE IS db2gse.ST_Geometry AS BLOB(1000) shape_buffer;
EXEC SQL END DECLARE SECTION;

// set the transform group for all subsequent SQL statements
EXEC SQL
   SET CURRENT DEFAULT TRANSFORM GROUP = ST_Shape;

// initialize host variables
... 

SET CURRENT DEFAULT TRANSFORM GROUP = ST_Shape;

// insert geometry using shape representation 
// into column of type ST_Geometry
EXEC SQL
     INSERT
	   INTO transforms_sample(id, geom)
	   VALUES ( :id, :shape_buffer );