Re: Unique Key

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Tue, 27 Jul 1999 21:58:07 +0800
Message-ID: <379DBAEF.1898@yahoo.com>

Lothar Armbrüster wrote:
>
> Juan Carlos wrote on 27-Jul-99 23:00:06:
> >We want to create a xref table for SSN and an Employee ID which will be
> >different. The table will just be those two columns. But I have a
> >dilemma. If I make SSN the PK, this would allow duplicate Employee
> >ID's. If I make it a composite PK, it would be possible to have
> >duplicate SSN's but different Employee ID's. Is there a way to make
> >the unique and distinct at the same time without triggers? JerryTWP: el
> >subject debe ser "Unique Key"
>
> Yes, there is a way:
>
> 1. Set the PK to SSN
> 2. Create an additional unique index on Emp ID
>
> This should solve your problem.
>
> Hope that helps,
> Lothar
>
> --
> Neue Adresse ab 10.07.'99:
> Lothar Armbrüster | lothar.armbruester_at_rheingau.netsurf.de
> Hauptstr. 26 | lothar.armbruester_at_t-online.de
> D-65346 Eltville |

It would advisable to create a unique constraint as opposed to a unique index. I saw some Oracle blurb a while ago that said Oracle may no longer support unique indexes as such in the future (although a unique constraint is implemented with a unique index anyway!)

HTH
--

---

Connor McDonald
"These views mine, no-one elses etc etc" connor_mcdonald_at_yahoo.com

"Some days you're the pigeon, and some days you're the statue." Received on Tue Jul 27 1999 - 08:58:07 CDT