Output of Null-Capable Fields in the Trigger Buffer

Hi, 
is there a way to find out the position-number of an field in my
database file?

I created a before trigger (insert and update) to manipulate 
some fields in our files like ID-Number, WriteDate, WriteTime,
UpdateDate, Update Time and so on. 

But some of these fields are null-capable. When a null-capable field is 
output to or updated in the trigger new record image, then if the
field is null, the value placed in the buffer will be ignored by data 
management.
These fields have the null indicator on in the trigger new null record map: 
This is
the map of the null record fields of my database file. This character array has 
the
same length as the number of fields in the database file associated to the 
trigger
program. DB2/400 can set each character to 1 (NULL field) or 0 (not NULL). 

How can I find out the position of the field in my database file to set the null
indicator off? I need a softcoding version because I don t want to hardcode
the position number.

In IBM s Redbook "DB2/400 Advanced Database Functions" theres is an example
of softcoding the trigger buffer. This means that if for some reason you change 
the structure of the
physical file, you also need to change the structure of the physical file 
inside the
trigger program. This must be repeated for all the trigger programs where the
structure of the related table has changed. The alternative is that at the time 
of
writing the trigger program, you do not hard code the structure of the table but
soft-code it. That way if and when you change the structure of a table, you only
need to recompile the trigger program and not make any changes to the trigger
program itself.

Example:

********************************************************
* TRIGGER BUFFER data structure
********************************************************
D TgBufDs                DS 
.....
D TgAftOfs                                         Like( TypeBin4 )
D TgAftLen                                        Like( TypeBin4 )
D TgAftNulOf                                     Like( TypeBin4 )
D TgAftNulLn                                     Like( TypeBin4 )
D TgBufChr                 1     32767A 
D TgBufAry                                1A    Overlay( TgBufChr )
D                                                        DIM ( %Size( TgBufChr 
) )

***********************************************************
* Data Structures for the Before and After images
***********************************************************
D BfCustomer E DS ExtName( Customer ).
D                             Prefix( Bf )
D                             Based( TgBfrPtr )
D AfCustomer E DS ExtName( Customer ).
D                             Prefix( Af )
D                             Based( TgAftPtr )


*****************************************************
* LETS EVALUATE THE VALUE OF THE POINTERS FOR THE BEFORE
* AND AFTER IMAGES .
***********************************************************
C Eval TgBfrPtr = %Addr(TgBufAry(TgBfrOfs + 1))
C Eval TgAftPtr = %Addr(TgBufAry(TgAftOfs + 1))


Thanks in advance.
Alexander.

Alexander Brand
brand@ireks.com 
http://www.ireks.com 



+---
| This is the RPG/400 Mailing List!
| To submit a new message, send your mail to RPG400-L@midrange.com.
| To subscribe to this list send email to RPG400-L-SUB@midrange.com.
| To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---