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Extending HCL OneDB™Beyond standard relational database objects, HCL OneDB™ can be extended to handle specialized data types, access methods, routines, and other objects. HCL OneDB™ includes many built-in extensions that are fully integrated in the database server. HCL OneDB™ also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for HCL OneDB™.
Creating extensionsYou can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in HCL OneDB™ databases.
DataBlade® API Function ReferenceThe HCL OneDB™ DataBlade® API Function Reference describes the DataBlade® API functions and the subset of functions that the DataBlade® API supports.
Function descriptionsThis section gives comprehensive reference information about the functions that are valid within DataBlade® API modules. It lists the function descriptions in alphabetical order, with syntax, usage information, and return values for the functions.
The mi_fp_argisnull() functionThe mi_fp_argisnull() accessor function determines whether the argument of a user-defined routine is an SQL NULL value from its associated MI_FPARAM structure.

The mi_fp_argisnull() function

The mi_fp_argisnull() accessor function determines whether the argument of a user-defined routine is an SQL NULL value from its associated MI_FPARAM structure.

Syntax

mi_unsigned_char1 mi_fp_argisnull(fparam_ptr, arg_pos)
   MI_FPARAM *fparam_ptr;
   mi_integer arg_pos;

fparam_ptr: A pointer to the associated MI_FPARAM structure.
arg_pos: The index position into the null-argument array for the argument to check for a NULL value.


Valid in client LIBMI application?	Valid in user-defined routine?
Yes	Yes

Usage

The mi_fp_argisnull() function determines whether the routine argument at position arg_pos in the MI_FPARAM structure that fparam_ptr references contains the SQL NULL value. The MI_FPARAM structure stores information about whether routine arguments contain the NULL value in the zero-based null-argument array. Therefore, to obtain information about the nth argument, use an arg_pos value of n-1. For example, the following call to mi_fp_argisnull() determines whether the third argument of the my_func() UDR is NULL:

mi_integer my_func(..., fparam1)
   ...
   MI_FPARAM *fparam1;
{
   ...
   if ( mi_fp_argisnull(fparam1, 2) == MI_TRUE )
      /* code to handle NULL argument */

Routines that handle NULL arguments must be registered with the HANDLESNULLS routine modifier of the CREATE FUNCTION or CREATE PROCEDURE statement.

For more information about argument information in an MI_FPARAM structure, see the HCL OneDB™ DataBlade® API Programmer's Guide.

Return values

MI_TRUE: The argument at position arg_pos is NULL.
MI_FALSE: The argument at position arg_pos is not NULL.
MI_ERROR: The function was not successful.