Re: [pgsql-general] Daily digest v1.9081 (14 messages)

On Mon, Jun 08, 2009 at 08:08:02PM +0100, Oliver Kohll - Mailing Lists wrote:
> On 8 Jun 2009, at 17:23, Merlin Moncure <mmoncure@gmail.com> wrote:
>
>>>> Is there a way when creating a table to limit it to one row?  That
>>>> is,
>>>> without using a stored procedure?
>>>>
>>>> I searched the documentation, but didn't find anything.
>>>>
>>>
>>>
>>> CREATE TABLE x (...);
>>>
>>> CREATE UNIQUE INDEX x_only_one_row ON ((1));
>>
>> very clever :D
>>
>> merlin
>
> To clever for me, I don't understand what's going on and can't
> replicate it in my 8.3.  Any expansion?

This should actually read:

CREATE UNIQUE INDEX x_only_one_row ON x((1));

This creates a unique expressional index on the table.  This
expression evaluates as true only in cases where the table has at most
one row, independently of what the possible row contains.

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter      XMPP: david.fetter@gmail.com

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