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From: bsa@telotech.UUCP (Brandon S. Allbery)
Newsgroups: comp.databases
Subject: Re: Ingres and referential integrities
Keywords: Ingres referential integrities
Message-ID: <1989Jul31.180936.9242@telotech.uucp>
Date: 31 Jul 89 18:09:36 GMT
References: <3081@rti.UUCP> <3225@rtech.rtech.com> <9677@alice.UUCP>
Sender: bsa@telotech.uucp (Brandon S. Allbery)
Reply-To: bsa@telotech.UUCP (Brandon S. Allbery)
Distribution: comp
Organization: _
	      telotech, inc. - Beachwood, OH
Lines: 32
In-reply-to: debra@alice.UUCP (Paul De Bra)

In article <9677@alice.UUCP>, debra@alice (Paul De Bra) writes:
+---------------
| Then referential integrity (given EMPNO is a key in EMP and DNO a key in
| DEPT) would imply that EMP cannot contain a DNO which does not occur in
| DEPT.
| 
| There should be no need for procedures or other low-level tricks to
| enforce this constraint.
+---------------

Why?  Because referential integrity is, by natural law, the lowest-level form
of integrity possible?

Multi-table integrity via procedures allows you to define referential
integrity.  Moreover, it allows you to define forms of integrity which a
hierarchical DBMS can not handle:  for example, a database I designed once
required the condition for integrity to be "... between xxx and yyy" instead
of simply "=".  Certainly, I could have designed it otherwise... and then
would have been forced to explain why the database had to be fed magic codes
instead of the values everyone was used to.  Sorry, folks, but forcing people
to conform to the DBMS's way of doing things isn't what I consider the right
way to do things.  (...segue to comp.info-systems....  1/2 :-)

RTI's got it right:  their system permits referential integrity as *you*
define it as a specific case of a much more general mechanism.

++Brandon
-- 
  Brandon S. Allbery @ telotech, inc.   (I do not speak for telotech.  Ever.)
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