Re: What is the use of a primary key?

Hi Lauri,

You wrote:
>
> >
> >
> >David Cressey wrote:
> >
> >
> >
> >>In fact, in Oracle, when you declare a PRIMARY KEY, you get an index on
> >>that key, like it or not.
> >>
> >>
> >
> >Seems odd that you'd have a quibble with this (and it's not
> >just limited to Oracle). Since a primary key must be unique,
> >how else would you want to enforce its uniqueness?
> >
>
> You might want to give properties (other than default) to the index, our
> you
> might want to set the order of some columns to descending.
>
> Now you have to first drop the system generated index and then create a
> new one.

At least part of what you want to achieve (storage parameters) can be done at index (and constraint) creation time by means of the keyword 'USING', after which you can specify a number of index specifics. You couldn't set the order to be descending, but frankly I wouldn't see a lot of use for that (index is supposed to be symmetric, isn't it?).

Regards,

Ruud de Koter.

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Ruud de Koter                    HP OpenView Software Business Unit
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