Purpose
Set the value of a Geometry type using a Well-Known Binary (WKB) BLOB represented by a LOB_RESULT_LOCATOR.
Syntax
void FNC_GeomGetWKBBlob(GEO_HANDLE geoHandle, LOB_RESULT_LOCATOR geoBlob, int srid)
- GEO_HANDLE 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.
- LOB_RESULT_LOCATOR geoBlob
- LOB locator for the WKB BLOB containing the return value for the ST_Geometry type.
- int srid
- Spatial Reference System Identifier of the Geometry to be set.
Usage Notes
FNC_GeomSetWKBBlob sets the ST_Geometry return/OUT/INOUT parameter value using a LOB result locator. The ST_Geometry Handle geoHandle is passed as input along with a LOB result locator geoBlob. The geoBlob locator value is obtained by calling FNC_GeomGetResultWKBBlob, and LOB FNC routines are used to append the WKB to the BLOB. It is then passed to FNC_GeomSetWKBBlob.
FNC_GeomSetWKBBlob should be used only with a LOB-based ST_Geometry value. Otherwise a 7579 error is generated: FNC_GeomSetWKBBlob is only valid for LOB-based ST_Geometry values. Use FNC_GeomSetWKB() instead.
Example: Using FNC_GeomGetResultWKBBlob and FNC_GeomSetWKBBlob to retrieve and set the value of a return ST_Geometry
The following function takes a ST_Geometry parameter and returns an ST_Geometry that has the same value. It first retrieves the Well-Known Binary format from the input geometry. It then retrieves the LOB result locator from the return ST_Geometry, appends the WKB to it, and then sets the value of the return ST_Geometry.
#define SQL_TEXT Latin_Text #include <sqltypes_td.h> #include <string.h> void geo_wkb( GEO_HANDLE *geo_in, GEO_HANDLE *geo_out, int *indicator_geo_in, int *indicator_geo_out, char sqlstate[6], SQL_TEXT extname[129], SQL_TEXT specific_name[129], SQL_TEXT error_message[257]) { LOB_RESULT_LOCATOR geoBlob_out; LOB_LOCATOR geoBlob_in; BYTE buffer[64000]; LOB_CONTEXT_ID id; FNC_LobLength_t actlen; int trunc_err = 0; FNC_LobLength_t blob_length; int srid = -1; int max_length, max_length2, numLobs, numLobs2; /* If input is null set return value to null. */ if (*indicator_geo_in == -1 ) { *indicator_geo_out = -1; return; } /* Get the Input Geometry Info */ FNC_GetGeometryInfo(*geo_in,&max_length, &numLobs); /* Get the Output Geometry Info */ FNC_GetGeometryInfo(*geo_out,&max_length2, &numLobs2); /* * Copy geo_in ST_Geometry value to geo_out ST_Geometry value. * */ if(numLobs ==1 && numLobs2 ==1) { /* Get the LOB_RESULT_LOCATOR of geo_out. */ FNC_GeomGetResultWKBBlob(*geo_out, &geoBlob_out); /* Get the LOB_LOCATOR and srid of the input ST_Geometry value. */ FNC_GeomGetWKBBlob(*geo_in, &geoBlob_in, &srid); FNC_LobOpen(geoBlob_in, &id, 0, 0); blob_length = FNC_GetLobLength(geoBlob_in); while (FNC_LobRead(id, buffer, blob_length, &actlen) == 0 && !trunc_err) trunc_err = FNC_LobAppend(geoBlob_out, buffer, actlen, &actlen); FNC_LobClose(id); /* Set the return ST_Geometry value */ FNC_GeomSetWKBBlob(*geo_out, geoBlob_out, srid); } }