I see your point, it is ok to have a unique key constraint on the Name
column, but bare in mind as others pointed out that you must handle the
problem when there are two same names that point to a different entity. You
may want the user to enter a unique number behind the name.

On Mon, Aug 15, 2011 at 11:53 PM, W O <sistemas2000profesional@...>wrote:

> Lester and Mark, thank you for your answers.
>
> I have a Primary Key on the ID column of those tables and a Unique Key on
> the Name column.
>
> I want to avoid duplicates forcing the names being different. If a user
> want
> to save a duplicate name then he/she will have a a message of advice. So,
> he/she will take the appropiate means.
>
> Greetings.
>
> Walter.
>
>
>
> On Mon, Aug 15, 2011 at 4:06 AM, Mark Rotteveel <mark@...
> >wrote:
>
> > **
> >
> >
> > On Mon, 15 Aug 2011 00:03:28 -0300, Alexandre Benson Smith
> >
> > <iblist@...> wrote:
> > > Em 14/8/2011 23:43, W O escreveu:
> > >> Hello everybody
> > >>
> > >> I had unique key restrictions on the column "Name" of tables like:
> > >> Countries, States, Banks, etc.
> >
> > Not sure if it is wise to do that; it really depends on the business
> rules.
> >
> > A politically controversial example: two countries claim to be China
> (where
> > at least one denies the existence/independence of the other).
> > In The Netherlands and Belgium we both have a province called 'Limburg'.
> > Different banks in different countries can have the same name (for
> example
> > in the last century both The Netherlands and Germany had a
> > 'Rafeissenbank'); or the branches of a single bank in different countries
> > are actually two distinct legal entities and need to be recorded as such;
> > there are cooperative banks where each bank is independent, but they do
> > share the same name (and some of the marketing and backoffice stuff).
> >
> > On the other hand, not enforcing some type of rules could mean actual
> > duplicated data.
> >
> >
> > >> So, I can avoid duplicates.
> > >>
> > >> What do you think, is it correct to use unique keys for that job?
> > >>
> > >> Greetings.
> > >>
> > >> Walter.
> > >>
> > >
> > > It depends on the business rules...
> > >
> > > I don't think that a unique constraint on the Field Name of a table of
> > > people is ok.
> > >
> > > We al lknow that there is more than one John Smith in the world.
> >
> > Agreed. It can lead to some nice problems if you would enforce that.
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>
>
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--
Iwan Cahyadi Sugeng


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