Unique constraints and unique indexes work together, but they
are different things conceptually speaking. They are like
buildings and elevators. The taller the building, the more you
need elevators, the more records you need to uniquely constrain,
the more you need an unique index.




--- Ernesto Cullen <ecullen@...> escreveu: > Martijn,

> if you declare a unique constraint, doesn't it creates a
> unique index to
> enforce the constraint?
>
> 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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