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From exxos <hat...@gmail.com>
Subject Re: How to tell that a rows is UNIQUE ?
Date Wed, 18 May 2011 19:53:56 GMT
Hej Rainer,

I noticed this, but here it was about defining a column in a table that is
not allowed to contain the same value twice. The index seems dedicated for
that issue.

Regards,
exxos.


On Wed, May 18, 2011 at 9:26 PM, Rainer Döbele <doebele@esteam.de> wrote:

> Hi exxos,
>
> I don't quite understand your question.
> What do you consider a unique column?
>
> Some databases allow integer columns that are automatically populated from
> a sequence (e.g. identity columns in Microsoft SQL).
>
> Another feature in Microsoft sql is the data type "uniqueidentifier" which
> is a guid that will be automatically generated for each row.
>
> For those two cases Empire-db offers the data types DataType.AUTOINC and
> DataType.UNIQUEID.
> The exact implementation however is database specific. The Oracle driver
> e.g. will create a number column and automatically create a sequence for
> AutoInc columns (on DDL generation).
>
> Does this answer help you?
>
> Regards
> Rainer
>
>
> Exxos wrote:
> > from: exxos [mailto:hatufr@gmail.com]
> > to: empire-db-user@incubator.apache.org
> > re: How to tell that a rows is UNIQUE ?
> >
> > Hello,
> >
> > At the colomn declartion in DBTable, how to tell that a colomn is unique
> ?
> > (I'm not talking about primaries keys)
> >
> > Regards,
> > exxos.
>

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