Informix DataBlade API Programmer's Manual DataBlade API Function Descriptions

The mi_funcarg_get_colno() function determines whether the expensive-UDR argument of a cost or selectivity function contains the SQL NULL value.

mi_boolean mi_funcarg_isnull(funcarg_ptr)

MI_FUNCARG *funcarg_ptr;

funcarg_ptr

is a pointer to the MI_FUNCARG structure that describes the expensive-UDR argument.

Valid in Client LIBMI Application?	Valid in User-Defined Routine?
No	Yes

The mi_funcarg_isnull() function determines whether the argument from the MI_FUNCARG structure that funcarg_ptr references contains the SQL NULL value. The MI_FUNCARG structure describes an argument of an expensive UDR to its cost or selectivity function. Use the mi_funcarg_isnull() function only for expensive-UDR arguments that are constant values; that is, only arguments for which the mi_funcarg_get_argtype() function returns the MI_FUNCARG_CONSTANT value.

Use the mi_funcarg_isnull() function in a cost or selectivity function to determine if the value of an argument passed into the expensive UDR is the SQL NULL.

See the descriptions of the following functions: mi_funcarg_get_argtype(), mi_funcarg_get_colno(), mi_funcarg_get_constant(), mi_funcarg_get_datalen(), mi_funcarg_get_datatype(), mi_funcarg_get_distrib(), mi_funcarg_get_routine_id(), mi_funcarg_get_routine_name(), and mi_funcarg_get_tabid().

For more information, see Creating Selectivity and Cost Functions.