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Re: Test if Data for a Field is UNIQUE

From: Andy Hassall <andy_at_andyh.co.uk>
Date: Mon, 23 Jan 2006 22:28:53 +0000
Message-ID: <9jlat19jinkh332ob1sbpcvtjslpd68q9f@4ax.com>


On Mon, 23 Jan 2006 16:57:36 -0500, Walt <walt_askier_at_SHOESyahoo.com> wrote:

>Mladen Gogala wrote:
>
>> BTW, you don't need unique index to have a unique constraint.
>
>Well, yes and no. In theory it is possible to have a unique constraint
>without an index. But Oracle will create an index for you when you
>create a unique constraint. You can test this by creating a unique
>constraint and querying the all_indexes table. There's an index there
>with your constraint name.

 Yes, but the _index_ doesn't have to be unique, which opens up possibilities such as deferrable constraints.

-- 
Andy Hassall :: andy@andyh.co.uk :: http://www.andyh.co.uk
http://www.andyhsoftware.co.uk/space :: disk and FTP usage analysis tool
Received on Mon Jan 23 2006 - 16:28:53 CST

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