Re: The wisdom of the object mentors (Was: Searching OO Associations with RDBMS Persistence Models)

From: Erwin <>
Date: 8 Jun 2006 06:19:21 -0700
Message-ID: <>

> Are you suggesting that RDBs cannot have duplicate rows, or even
> duplicate tables?

You seem to be obviously ignorant of the fact that duplicate "rows" (as you call them) are indeed very much ruled out by the relational model. And of the fact that this has been the case ever since the model was first defined. As a certain person named "Ted Codd" (whom maybe you might have heard of, by accident) once put it : "if something is true, then saying it twice will not make it any truer.".

Where :

'something' : a fact in the real world, e.g. "Robert Martin is a male". 'saying it twice' : inserting two identical rows ("Robert Martin",male) in the same table.

It's pointless.

And so is retaining duplicate rows in "derived" or "computed" tables. Received on Thu Jun 08 2006 - 15:19:21 CEST

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