Re: Adding another primary key to a populated table

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От Aaron Koning
Тема Re: Adding another primary key to a populated table
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Msg-id 1319fbba0601052244s7ad7920ei86ee787f064211a1@mail.gmail.com
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Ответ на Re: Adding another primary key to a populated table  (Daniel Kunkel <DanielKunkel@BioWaves.com>)
Ответы Re: Adding another primary key to a populated table  (Daniel Kunkel <DanielKunkel@BioWaves.com>)
Список pgsql-general
Are you trying to create a primary key composed of 6 fields? What is the result you want to achieve with the constraint? If you just want UNIQUE, NOT NULL values in a field, you can achieve that without creating a primary key.

Aaron

On 1/5/06, Daniel Kunkel <DanielKunkel@biowaves.com> wrote:
Hi

It makes sense that I can't have more than 1 primary key.

Postgres was trying to create another primary key instead of modify the
existing primary key.

So...

As I understand it, a table does not always have to have a primary key
defined.

Would it work to first delete/drop the primary key, then recreate the
primary key on all 6 columns.

ALTER TABLE product_price DROP CONSTRAINT  product_price_pkey;

I tried this, but it doesn't seem to work...  If I look at the table
from pgAdmin, it is still there, reindexable, I can't add a new primary
key, etc.  But if I try to run the above command twice, it says it's
already been removed.

--

Just for the record...  the error message I got was:

ERROR:  ALTER TABLE / PRIMARY KEY multiple primary keys for table
'product_price' are not allowed


On Fri, 2006-01-06 at 05:19 +0000, Andrew - Supernews wrote:
> On 2006-01-06, Daniel Kunkel < DanielKunkel@BioWaves.com> wrote:
> > Hi
> >
> > I'm trying to add another primary key to a table populated with data and
> > a number of foreign key constraints.
>
> You can only have one primary key on a table.
>
> You can add additional unique constraints to get the same effect. (A
> primary key constraint is just a unique constraint that is also not null,
> and is the default target for REFERENCES constraints referring to the table -
> this last factor is why there can be only one...)
>


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