Absolutely do not use ssn for a primary key. I ran into that as a
concern when I created a report. The ssn can be assummed by another
person, and you would have two persons with the same ssn. Plus the
already mentioned recycle of the ssn. I know of cases where the ssn
is taken by a person entering into the US to get work.
- "Koivu, Lisa" <lisa.koivu_at_efairfield.com> wrote:
> Well, here's one problem - there is no guarantee that Social
> Security Number
> will indeed be unique. SS#'s are reassigned, just like phone
> numbers are.
>
> IMHO, surrogate keys are always a good idea. Has anyone got an
> example of
> when a surrogate key is NOT a good idea?
>
> > Lisa Koivu
> > Oracle Database Administrator
> > 954-935-4117
> >
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> >
> > -----Original Message-----
> > From: Rao, Maheswara [SMTP:Maheswara.Rao_at_Sungardp3.com]
> > Sent: Tuesday, June 12, 2001 9:21 AM
> > To: Multiple recipients of list ORACLE-L
> > Subject: RE: Enforced Costraints ??
> >
> > In a DSS environment, it is a standard practice to create
> surrogate keys
> > for
> > primary key. I never had experience with this (having duplicates
> in PK).
> > Perhaps a list member could tell what probs might arise.
> >
> > Rao
> >
> > -----Original Message-----
> > Sent: Tuesday, June 12, 2001 6:26 AM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Not good enough ! According to various documents, you should add
> your own
> > primary key (surrogate key), which also makes it easier to keep
> track of
> > history and combine various sources. I agree with Lee: you should
> never
> > implement a PK with non-unique values.
> >
> > Remco
> >
> > -----Oorspronkelijk bericht-----
> > Van: Rahul [mailto:rahul_at_ratelindo.co.id]
> > Verzonden: dinsdag 12 juni 2001 11:56
> > Aan: Multiple recipients of list ORACLE-L
> > Onderwerp: RE: Enforced Costraints ??
> >
> >
> > DSS !
> >
> >
> > > ----------
> > > From: Robertson Lee - lerobe[SMTP:lerobe_at_acxiom.co.uk ]
> > > Reply To: ORACLE-L_at_fatcity.com
> > > Sent: Tuesday, June 12, 2001 4:00 PM
> > > To: Multiple recipients of list ORACLE-L
> > > Subject: RE: Enforced Costraints ??
> > >
> > > am I missing something here ?? Why would you ever need to be in
> that
> > > situation (a table with non-unique values in a PK column) ?
> > >
> > > Apologies if this is a no-brainer.
> > >
> > > Lee
> > >
> > >
> > > -----Original Message-----
> > > Sent: 12 June 2001 09:41
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > > i think the solution is to .....
> > >
> > > (on a table with non-unique values in a PK candidate column)
> > >
> > > 1) create a non-unique index on the pk candidate colunm
> > > 2) create the pk using enable novalidate clause
> > >
> > > this way the existing data will NOT checked for uniqueness, the
> > constraint
> > > will be "enforced" for the upcoming data only...
> > >
> > > Regards
> > > Rahul
> > >
> > >
> > > > > ----------
> > > > > From: Anshumn[SMTP:anshumn.sagar_at_wipro.com]
> > > > > Sent: Tuesday, June 12, 2001 12:30 PM
> > > > > To: Rahul
> > > > > Subject: Re: Enforced Costraints ??
> > > > >
> > > > > Hi Rahul,
> > > > >
> > > > > That is true. In Oracle 8, there is option to enable the
> constraint
> > in
> > > > > novalidate mode or validate mode. The novalidate mode is
> the enforce
> > > > mode,
> > > > > where only the forthcoming data is checked. It does not
> check the
> > > > exisitng
> > > > > data. The validate mode is the normal constraint enable
> mode.
> > > > >
> > > > > The syntax is
> > > > > Alter table table enable novalidate constraint name;
> > > > >
> > > > > So after I put the constraint in the novalidate mode, the
> uniqueness
> > > > will
> > > > > be checked only amongst the coming data. But if later I set
> the
> > > > constraint
> > > > > ti validate mode(enable), then it may give error as the
> loaded data
> > > was
> > > > > never checked for uniqueness with the exisitng data. In
> this case I
> > am
> > > > > very much confused with the usefulness of this feature.
> > > > > Can you please give any inputs for the same to clear my
> doubts ?
> > > > >
> > > > > Thanks & Regards,
> > > > > Anshumn
> > > > >
> > > > > Rahul wrote:
> > > > >
> > > > > Anshuman,
> > > > >
> > > > > whenever u add a constraint to a table, oracle will make
> > sure all
> > > > > the data
> > > > > (if any)
> > > > > confirms to the constraint added....
> > > > >
> > > > > you can enable or disable a constraint (even defer)...
> dont
> > confuse
> > > > > urself
> > > > > with the term "enforcing a constraint".
> > > > >
> > > > > Regards
> > > > > Rahul
> > > > >
> > > > > > ----------
> > > > > > From: Anshumn[SMTP:anshumn.sagar_at_wipro.com]
> > > > > > Sent: Tuesday, June 12, 2001 11:26 AM
> > > > > > To: LazyDBA.com Discussion
> > > > > > Subject: Enforced Costraints ??
> > > > > >
> > > > > > Hi gurus,
> > > > > >
> > > > > > Please help me to know the difference between enabling
> and
> > > > > enforcing a
> > > > > > constraint. I need it urgently.
> > > > > >
> > > > > > As per my knowledge, enabling a constraint checks for
> the
> > > > > > existing data to apply that constraint and then the
> > constraint is
> > > > > > applied for the forthcoming data. Whereas enforcing a
> > constraint
> > > > > does
> > > > > > not check the existing records and the constraint is
> only
>
=== message truncated ===
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