Re: Primary key

In article <39a4023b$1_at_rpc1284.daytonoh.ncr.com>,   "Jim Gregory" <JG200024_at_NCR.com> wrote:
> I'm not really sure what you're asking. ORACLE would not make fieldz
 part
> of the primary key unless it were not null. You could add the column,
> populate it so that the combination of x,y,z would be unique, alter
 table
> modify z not null, and then drop the current primary key and define a
 new
> one using all 3 fields.
>
> The only consequence is that now you have a 3 field PK instead of a 2
 field.
> Any application code would have to be modified to take that into
 account.
>
> --
> Jim Gregory
> Principal Consultant for Keane, Inc.
> Currently assigned to NCR
> "Opinions are my own and do not reflect
> those of Keane or my clients"
> Lim Chin Yee <ccelimcy_at_nus.edu.sg> wrote in message
> news:3447D7F0AFD4D011AE0400608C14CE561F3C638D_at_pfs01.ex.nus.edu.sg...
> > Table A's primary key is made up of 2 fields( fieldx and fieldy)
> > If i were to add in a new field(fieldz) and make it a primary key as
> > well,
> > what are the consequences?
> >
> > consequences that i've thought of.
> > 1. since fieldz is of null value, existing data cannot be validated
> > since the constraints cannot work.
> >
> >
> >
> > p.s: all 3 fields shld be NON-NULL
> >
> > TIA
> >

and any indexes you create or populate will be affected as well.

sonya

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Before you buy. Received on Wed Aug 23 2000 - 14:45:47 CDT