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From: Eric de Jonge <ejonge@tpd.TNO.NL>
To: post list <postgres@postgres.Berkeley.EDU>
Cc: Eric de Jonge <ejonge@tpd.TNO.NL>
Subject: new type & rule ?!
Date: Wed, 15 Jun 1994 13:21:14 +0200 (MET DST)
Message-ID: <9406151121.AA05432@tpdusv.tpd.tno.nl> (raw)

I've defined :
- new data type IMAGEOBJ
- operator '=' to test if IMAGEOBJ = text

Example:

create imclass(field=IMAGEOBJ)
create teclass(field=text)

contents:

IMCLASS:
---------------
| field       |
---------------
| db_600629   |
---------------
| db_600636   |
---------------
| db_600643   |
---------------

TECLASS:
---------------
| field       |
---------------
| db_600629   |
---------------
| db_600636   |
---------------
| db_600643   |
---------------


AND NOW: define rule cascades is on delete to imclass 
         do delete teclass where current.field = teclass.field

So, on delete of an instance in imclass, the instance which's equal is also
removed.

COMMAND: delete imclass where imclass.field = "db_600643"

RESULT: remove the last instance of imclass and teclass

REALITY: ALL the instances of teclass were REMOVED!!



Conclusion : define a rule for built-in data types with CURRENT works;
          => define a rule for new data types with CURRENT not?!

Is this right?
-- 
_/ Eric de Jonge
_/ Email: ejonge@tpd.tno.nl 

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