|
A constraint can only compare columns or values within the same row in
the same table.
If you need to compare a value with values located in other tables, you
may write a before insert/update triggers that compares the incoming
value with the allowed values and returns an error if the value does
not match.
Mit freundlichen Grüßen / Best regards
Birgitta Hauser
"Shoot for the moon, even if you miss, you'll land among the stars."
(Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok) "What
is worse than training your staff and losing them? Not training them
and keeping them!"
-----Ursprüngliche Nachricht-----
Von: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von
rpglist@xxxxxxxxxxx
Gesendet: Wednesday, 19.9 2012 23:27
An: midrange-l@xxxxxxxxxxxx
Betreff: Constraint based upon a separate file
I know how to add a typical check constraint where it ensures that the
value matches a short list of codes, etc. I have been searching for
the past few hours to no avail for an example that shows how to add a
check constraint based upon the value in a separate file:
Quick and dirty example would be a state field of two characters that
has to match a predfined table of state abbrev's or a zipcode lookup
table...
Does anyone have any examples I can reference? I have been all over
the reference manual and so far haven't found what I'm looking for.
Thanks,
C
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