Re: unique constraints

From: Abiy Alemu <alemu_at_cril-ing.fr>
Date: Fri, 09 Apr 1999 09:27:51 +0200
Message-ID: <370DABF7.C52172B@cril-ing.fr>

Why does the statement

Create Unique Index <Index_name> on <Table_name>(<Column1>, <Column2>) fails

on an already existing table with data inside ?

Is there a work around for it ?

Bunyip wrote:

> Logically, a Null repersents an UNKNOWN value. Therfore it's value is unique
> in the sense that it is unknown.
>
> B.
>
> Prasad wrote in message <37074AB8.23FD_at_inspire.net.nz>...
> >Hai!
> >I want to know how oracle reads the null values
> >on a column defined with unique constraint . Plese clarify whether
> >null is treated as same or different on each row.
> >
> >I will be very much thankful for an early reply
> >kep
Received on Fri Apr 09 1999 - 02:27:51 CDT