If a UDF includes a user-supplied header file, the EXTERNAL clause in the CREATE FUNCTION statement must specify the name and path of the header file.
Consider the following function that includes the header file stypes.h:
/***** C source file name: substr.c *****/
#define SQL_TEXT Latin_Text
#include <sqltypes_td.h>
#include "stypes.h"
void udf_substr( VARCHAR_LATIN *inputString,
INTEGER *start,
VARCHAR_LATIN *result,
char sqlstate[6])
{
...
}
Here is an example of CREATE FUNCTION that specifies the name and path of the user-supplied header file:
CREATE FUNCTION udfSubStr (inputString VARCHAR(512), start INTEGER) RETURNS VARCHAR(512) LANGUAGE C NO SQL EXTERNAL NAME 'CI!stypes!udfsrc/stypes.h!CS!substr!udfsrc/substr.c!F!udf_substr' PARAMETER STYLE TD_GENERAL;
| String Part after EXTERNAL NAME | Meaning |
|---|---|
| ! | Delimiter. |
| C | Header file is obtained from client. |
| I | Information between following two sets of delimiters identifies name and location of include file (.h). |
| stypes | Name of header file, without file extension. |
| udfsrc/stypes.h | Path and name of header file on client. |
| C | Source is obtained from client. |
| S | Information between following two sets of delimiters identifies name and location of C or C++ function source file. |
| substr | Name server uses to compile source, without file extension. |
| udfsrc/substr.c | Path and name of source file. |
| F | Information after next delimiter identifies C or C++ function name. |
| udf_substr | C or C++ function name. |
See CREATE FUNCTION in Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144.