Re: Can I have check and referential constraint on same column?

Rick,

In your case, I'm afraid that the constraints would not apply...I think it
would only work if the check constraint can be seen as a subset of the
referential constraint. Maybe Rob's suggestion (triggers) would be more
helpful.

Regards,

Luis Rodriguez
IBM Certified Systems Expert — eServer i5 iSeries


On Thu, May 20, 2010 at 3:10 PM, <Rick.Chevalier@xxxxxxxxxxxxxxx> wrote:

I can add the constraints but it doesn't do what I need it to. I have a
check constraint of 'V' or blank and a referential constraint of 'P' or 'H'
(more to come later). The 'V' and blank are hard coded into the program
depending on certain conditions. If the user chooses an override the 'P' or
'H' will be used. Unfortunately they appear to be mutually exclusive.

I tried inserting a row using SQL and if I use one of the referential
constraint values the insert fails due to the check constraint. If I use
one of the check constraint values the insert fails due to the referential
constraint. The value has to satisfy both constraints.

It makes sense, it just doesn't work for me in this case.

Rick

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:
midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Luis Rodriguez
Sent: Thursday, May 20, 2010 1:49 PM
To: Midrange Systems Technical Discussion
Subject: Re: Can I have check and referential constraint on same column?

Rick,

To check my answer I did a small test:

ALTER TABLE MyLib/File1
ADD Constraint FK_CardType
FOREIGN KEY (CardType)
REFERENCES MyLib/File2 (CardType) ;

ALTER TABLE File1 ADD CHECK (CardType <> 9 ) ;

No problem in creating both constraints. Even if there is a CARDTYPE 9 in
File2, I can't insert a CARDTYPE 9 record in File1. The system returns
CPF502F (Check constraint violation).

Did not check what happens the CHECK constraint is created before the
foreign key...

HTH,
Luis Rodriguez
IBM Certified Systems Expert - eServer i5 iSeries

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