Hi,

> if you declare a unique constraint, doesn't it creates a unique index

to

> enforce the constraint?

Yes it does - but that's an implementation detail. There is a difference
though - an unique index cannot be used in an FK relation, while a
unique/pk constraint can.

And of course, there's the conceptual difference :-)

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com

> Ernesto Cullen
> ecullen@...
> http://www.infoback.com.ar/buhardilla
> Paraná, Entre Ríos
> Argentina
>
>
> ----- Original Message -----
> From: "Martijn Tonies" <m.tonies@...>
> To: <firebird-support@yahoogroups.com>
> Sent: Thursday, November 20, 2003 12:52 PM
> Subject: Re: [firebird-support] A basic consultation
>
>
> >
> > > Driver
> > > ===============================
> > > Driver_ID integer PK
> > > License_Number varchar(12) Unique index - NOT NULL
> >
> > Unique CONSTRAINT.
> >
> >
> > Indices are for speed, constraints for integrity.
>
>
>
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