Purpose
Set the value of a Geometry type using a Well-Known Text (WKT) CLOB represented by a LOB_RESULT_LOCATOR.
Syntax
void FNC_GeomGetWKTClob(GEO_HANDLE geoHandle, LOB_RESULT_LOCATOR geoClob, 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 geoClob
- LOB locator for the WKT CLOB containing the return value for the ST_Geometry type in the Latin character set.
- int srid
- Spatial Reference System Identifier of the Geometry to be set.
Usage Notes
The FNC_GeomSetWKTClob function 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 geoClob.. The geoClob locator value is obtained by calling FNC_GeomGetResultWKTClob, and LOB FNC routines are used to append the WKT value to the CLOB. It is then passed to the FNC_GeomSetWKTClob routine. The CLOB should be in the Latin character set.
FNC_GeomSetWKTClob should be used only with a LOB-based ST_Geometry value. Otherwise a 7579 error is generated: FNC_GeomSetWKTClob is only valid for LOB-based ST_Geometry values. Use FNC_GeomSetWKT() instead.
Example: Using FNC_GeomGetResultWKTClob and FNC_GeomSetWKTClob to retrieve and set the value of a return ST_Geometry
The following function takes an ST_Geometry parameter and returns an ST_Geometry that has the same value. It first retrieves the Well-Known Text format from the input geometry. It then retrieves the LOB result locator from the return ST_Geometry, appends the WKT to the CLOB, and then sets the CLOB into the return ST_Geometry.
REPLACE FUNCTION geo_wkt(p1 ST_Geometry) RETURNS ST_Geometry SPECIFIC geo_wkt NO SQL PARAMETER STYLE SQL DETERMINISTIC LANGUAGE C EXTERNAL NAME 'CS!geo_wkt!geo_wkt.c!F!geo_wkt'; #define SQL_TEXT Latin_Text #include <sqltypes_td.h> #include <string.h> void geo_wkt( 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 geoClob_out; LOB_LOCATOR geoClob_in; BYTE buffer[64000]; LOB_CONTEXT_ID id; FNC_LobLength_t actlen; int trunc_err = 0; FNC_LobLength_t clob_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_GeomGetResultWKTClob(*geo_out, &geoClob_out); /* Get the LOB_LOCATOR and srid of the input ST_Geometry value. */ FNC_GeomGetWKTClob(*geo_in, &geoClob_in, &srid); FNC_LobOpen(geoClob_in, &id, 0, 0); clob_length = FNC_GetLobLength(geoClob_in); while (FNC_LobRead(id, buffer, clob_length, &actlen) == 0 && !trunc_err) trunc_err = FNC_LobAppend(geoClob_out, buffer, actlen, &actlen); FNC_LobClose(id); /* Set the return ST_Geometry value */ FNC_GeomSetWKTClob(*geo_out, geoClob_out, srid); } }