RE: file changed

Referential constraints are a powerful tool.  But I'd have to have more 
information to go further.  For example if I have 

Custmast table
custnbr
...

Itemmast table
itemnbr
...

CustPart table
custnbr
itemnbr
custItemNbr  // we say potatoe the customer says potato
...

I would put two constraints on CustPart.  No brainer.
ADDPFCST FILE(CUSTPART) TYPE(*REFCST) KEY(CUSTNBR) PRNFILE(CUSTMAST)
ADDPFCST FILE(CUSTPART) TYPE(*REFCST) KEY(ITEMNBR) PRNFILE(ITEMMAST)

But how does one put a constraint to check that if we create a new item 
number, or a new customer number, to make sure that we have a customer 
item number to our item number part cross reference record?  A possible 
solution is to put a constraint on the order detail file.

orderDet table
orderNbr
LineNbr
custNbr
ItemNbr
...

ADDPFCST FILE(ORDERDET) TYPE(*REFCST) KEY(CUSTNBR ITEMNBR) 
PRNFILE(CUSTPART)

One minor quibble is how do we handle the rule that if there is no record 
in CustPart then just use our item#?  Or do we not, just as a safety 
precaution?
This might be a good point for a trigger instead of a constraint.  At 
least on the ORDERDET file.  Trigger that if they write a new record to 
the orderdet, and there is no matching CustPart then send an email to the 
inventory control specialist.


Rob Berendt