Re: Has E/R had a negative impact on db?
From: Jon Heggland <jon.heggland_at_idi.ntnu.no>
Date: Mon, 24 Apr 2006 08:53:36 +0200
Message-ID: <e2hslc$sfq$1_at_orkan.itea.ntnu.no>
Date: Mon, 24 Apr 2006 08:53:36 +0200
Message-ID: <e2hslc$sfq$1_at_orkan.itea.ntnu.no>
-CELKO- wrote:
> One problem is that a relationship in a ER diagram is a line between
> boxes. That puts us in a binary-only world. ORM, on the other hand,
> allows n-ary relationships.
Are you talking about Chen's original ER? Because most ER variants I've seen definitely allow n-ary relationships---and the relationship aren't the lines, they're the diamonds.
> And the diagram has no other information
> about the nature of the relationship, like ORM does.
This also depends on the ER dialect.
-- JonReceived on Mon Apr 24 2006 - 08:53:36 CEST