RE: Null Capable Fields

[boothm@xxxxxxxxxxxxxxxxx]

Now I am glad I asked the question; it really does amount to a request to 
detect and/or restore virginity.  I can see useful reasons for it, but in 
the example you've shown I came away thinking the real problem is that the 
decision is being removed from the point of original information.  When 
you learn the field is null, and know you need the knowledge later on, fly 
a traditional RPG flag.  There's no reason to lug nulls all around the 
C-specs and compound the lives of those maintenance programmers who come 
after us, is there? 

In any event, thank you all for the kindness of the replies and the 
thoroughness.




Please respond to RPG400-L@midrange.com
Sent by:        owner-rpg400-l@midrange.com
To:     RPG400-L@midrange.com
cc: 

Subject:        RE: Null Capable Fields

Booth,

Let me give
you an example:

Database file CUSTOMER stores end-user information.  It is keyed on 
CUSNUM.
Some customers are chain-stores, and their invoices go to the home office.
The home office information is also stored in CUSTOMER because the home
office can buy goods from us, too.  The chain-store points back to the 
home
office by a field called HOMNUM. The date of the last invoice is stored in
LSTINV.   Typical records look like this:

CUSNUM NAME          HOMNUM LSTINV
00001  Local Store 1 50000  *NULL
00002  Local Store 2 50000  19991012
00003  Independent   *NULL  19990601
50000  Home Office   *NULL  19991004

We're printing an invoice.  We have code to print the date of the last
invoice, or "Thanks for your first order!" if this is the first order
(%nullind(LSTINV) = *On)  We also need to go off to CUSNUM 50000 to get 
the
address of the home office.  This means that we need to save the contents 
of
LSTINV before doing HOMNUM CHAIN CUSTOMER. 



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