Specify null parameter for SQL UDF

["Peter Dow (ML)" <maillist@xxxxxxxxxxxxxxx>]

Hi Everyone,

How do I call a UDF with a null parameter? I have a UDF created to 
return the accounting month for a given date (the only parameter), but 
if no parameter is given, it will return the current accounting month.

It works fine when I pass it a date, e.g.

SELECT ACCTGMONTH(CURRENT_DATE) FROM ANYFILE

but complains (says it cannot find ACCTGMONTH) if I use it like this:

SELECT ACCTGMONTH() FROM ANYFILE

I understand that it identifies a UDF based on the name and the input 
parameter types, but I don't understand how to tell it a particular 
parameter may be optional.

I created it with the following:

create function UTLIB/ACCTGMONTH (date) returns integer
      language RPGLE                                 
      parameter style GENERAL WITH NULLS             
      not deterministic                              
      no SQL                                
      called on null input                           
      no external action                             
      external name 'UTLIB/SVCBUS(ACCTGMONTH)'

ACCTGMONTH is a procedure within a service program, with prototype like 
this:

d AcctgMonth...                            
d                 pr            10i 0      
d  amDate                         d   const
d  amDateNull                   10i 0      
d  amResultNull                 10i 0

*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
pdow@xxxxxxxxxxxxxxx <mailto:pdow@xxxxxxxxxxxxxxx> /