Re: Do I need a PK on a join table?

From: Alfredo Novoa <alfredo_novoa_at_hotmail.com>
Date: 15 Feb 2006 04:56:14 -0800
Message-ID: <1140008174.632670.286400@g47g2000cwa.googlegroups.com>

>> SQL and DB2 confound the issue by mixing physical structures (indexes)
>> with purely logical integrity constraints (uniqueness/keys), by allowing
>> the abominable NULL,

>I don't know where there is anything "mixed" and how NULL would fit into
>this statement. Could you possibly explain how you mean that?

I think that this is crystal clear. Indices are physical artifacts and keys are logical level integrity constraints. Nulls are an abomination that interfer with many things including integrity constraints.

>> If you have a strong argument for wanting no index, declare a uniqueness
>> constraint.

>Which will be enforced by a unique index...

Which could be implemented with the help of a unique index.

Regards
Alfredo Received on Wed Feb 15 2006 - 06:56:14 CST