Set the value of a Geometry type using a Well-Known Binary (WKB) representation of the Geometry.
Syntax
void FNC_GeomGetWKB(GEO_HANDLE geoHandle, byte* wkb, FNC_GeomSize_t wkbSize, int srid)
Syntax Elements
- geoHandle
- A handle to a Geometry type that is defined to be a return value for a UDF/UDM or an INOUT/OUT parameter to an external stored procedure.
- wkb
- A pointer to the WKB value to be set.
- wkbSize
- Size in bytes of the WKB value.
- srid
- Spatial Reference System Identifier of the Geometry to be set.
Usage Notes
FNC_GeomSetWKB sets the value of a Geometry using a WKB byte string. The wkb parameter containing the WKB string, the wkbSize and the SRID to be set for the Geometry are passed as input.
FNC_GeomSetWKB should be called only for inline ST_Geometry values. If used with a LOB-based ST_Geometry value, a 7579 error is generated: FNC_GeomSetWKB is only valid for inline ST_Geometry values.
Example: Using FNC_GeomGetWKB and FNC_GeomSetWKB to get and set a geometry WKB
The following UDF takes a ST_Geometry parameter as input, retrieves the WKB representation, and sets the return ST_Geometry value with it. It assumes the Geometry size is small enough to be read using a single read.
CREATE FUNCTION geomUDF3(P1 st_geometry)
RETURNS ST_GEOMETRY
NO SQL
PARAMETER STYLE SQL
DETERMINISTIC
LANGUAGE C
EXTERNAL NAME 'CS!geomUDF3!geomUDF3.c';
void geomUDF3(GEO_HANDLE* geom_handle,
GEO_HANDLE* return_handle,
int* indicator_thisGeom,
int* indicator_returnValue,
char sqlstate[6],
SQL_TEXT extname[129],
SQL_TEXT specific_name[129],
SQL_TEXT error_message[257] )
{
FNC_GeomSize_t geomsize;
FNC_GeomSize_t bytesRead;
FNC_GeomSize_t offset;
FNC_GeomSize_t size;
FNC_GeomSize_t wkbSize;
byte* wkbBuffer;
FNC_GeomSize_t wkbBufferSize;
int srid;
/* Get the Geometry WKT Size */
geomsize = FNC_GeomGetWKBSize(*geom_handle);
/* Read the WKB value */
wkbBuffer = (byte*)FNC_Malloc(geomsize);
wkbBufferSize = geomsize;
size = geomsize;
offset = 0;
/* Get the WKB value */
FNC_GeomGetWKB(*geom_handle,wkbBuffer, wkbBufferSize,
&wkbSize, &srid);
/* Set the return value */
FNC_GeomSetWKB(*return_handle, wkbBuffer, wkbSize,0);
*indicator_returnValue = 0;
FNC_free(wkbBuffer);
}