Data modeling question
- From: "Thomas Jeff" <jeff.thomas@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 11 May 2005 07:37:43 -0500
I was wondering if there was an elegant way to model (or implement the
business rule)=20
for those situations where the requirement in a parent-child
relationship is such=20
that there a quantity restriction on the child table. =20
Consider the following two tables:
Table A Table B
DB_NAME DB_NAME
SCHEMA_NAME SCHEMA_NAME
USR_ID -- user (authority)
AUTH_INDICATOR -- change authority
USR_INDICATOR -- user authority
In a nutshell, the rule is that there can be no more than 3 change or
user
authorities for the given database/schema. A given user can be either
or both a change=20
and user authority for a specific database/schema, and can be an
authority for multiple
database/schemas. So, given the model/business rule, there could be
anywhere from 3=20
to 6 child records for a given database/schema.
When first presented with this model, my initial thought was to add a
shadow table to Table B,=20
using before triggers to implement the business rules, and after
triggers to maintain the=20
shadow table.=20
I'm sure this problem has cropped up before and would appreciate knowing
how you implemented
such a requirement.
Thanks.
--------------------------------------------
Jeffery D Thomas
DBA
Thomson Information Services
Thomson, Inc.
Email: jeff.thomas@xxxxxxxxxxx
Indy DBA Master Documentation available at:
http://gkmqp.tce.com/tis_dba
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