Have you thought of something as simple as an additional column with a check constraint of values 1 thru 6? And then make this a part of the primary key of the child table:
Table B PK DB_NAME PK SCHEMA_NAME PK RECORD_NUMBER <=3D=3D=3D values of 1 thru 6 only. USR_ID -- user (authority) AUTH_INDICATOR -- change authority USR_INDICATOR -- user authority
Simple but effective.
Hope this helps.
Tom
-- --Original Message-- -- From: oracle-l-bounce@(protected) [mailto:oracle-l-bounce@(protected)] On Behalf Of Thomas Jeff Sent: Wednesday, May 11, 2005 8:38 AM To: oracle-l@(protected) Subject: Data modeling question
I was wondering if there was an elegant way to model (or implement the business rule)=3D20 for those situations where the requirement in a parent-child relationship is such=3D20 that there a quantity restriction on the child table. =3D20
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=3D20 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=3D20 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,=3D20 using before triggers to implement the business rules, and after triggers to maintain the=3D20 shadow table.=3D20
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.
