Path: utzoo!attcan!uunet!lll-winken!lll-lcc!unisoft!mtxinu!sybase!spider!jeffw
From: jeffw@spider.sybase.com (Jeffrey Ward)
Newsgroups: comp.databases
Subject: Re: Referential Integrity
Summary: The functionality exists, but not in the form you might want.
Keywords: CSDate, not just BLOCK
Message-ID: <2500@sybase.sybase.com>
Date: 27 Dec 88 19:46:11 GMT
References: <560@bloom.UUCP>
Sender: news@sybase.sybase.com
Reply-To: jeffw@spider.UUCP (Jeffrey Ward)
Followup-To: comp.databases
Distribution: na
Organization: Sybase, Inc.
Lines: 35

In article <560@bloom.UUCP> bobd@bloom.UUCP (Bob Donaldson) writes:
] The discussion on binary data types has prompted me to ask another feature-
] related question -
] 
] Why don't any of the RDBMS packages we all know and love REALLY support
] referential integrity??
] 
] HOLD ON - before you all chime in with 'but MINE does', let me say that I
] do NOT mean the simplistic approach that is so often implemented that
] merely prevents you from inserting or deleting a record that would 
] violate the principle.

Have you taken a look at the SYBASE system?  While the referential integrity
mechanisms used in this system are not implemented precisely the way that
you specify, SYBASE uses special database objects called "rules", "defaults",
and, in particular, "triggers" to control database integrity.

In particular, triggers are not used merely to prevent an insert or update
that conflicts with integrity rules; they can also be used to force cascading
inserts, updates, and deletes, print messages, rollback entire transactions,
make calls to stored procedures or (in the upcoming 4.0 release) remote stored
procedures on other server nodes, raise exceptions, make decisions on the
basis of the data or the operation, and so forth.

I believe that other vendors are also implementing trigger-like objects,
but I do not know what their schedules for implementation are.  It sounds
like this sort of database object fulfills your need for non-simplistic
referential integrity, even if it does not use precisely the mechanism
that you cite in your example.

-----------------------------------------------------------------------------
	Jeffrey Ward		{pacbell,mtxinu,pyramid}!sybase!jeffw
	Sybase, Inc.
	6475 Christie Avenue	Disclaimer:  The opinions expressed above may
	Emeryville, CA  94608	not even be my own, much less my employers'.
-----------------------------------------------------------------------------