modeling either/or relationship...
From: Volker Hetzer <volker.hetzer_at_ieee.org>
Date: Fri, 27 Jan 2006 12:39:47 +0100
Message-ID: <drd0q3$idc$1_at_nntp.fujitsu-siemens.com>
Hi!
I've got to model electrical constraints on a net of a pcb. So, a net can be constrained either by layer,net class (and constraint name) or constraint class (and constraint name).
Date: Fri, 27 Jan 2006 12:39:47 +0100
Message-ID: <drd0q3$idc$1_at_nntp.fujitsu-siemens.com>
Hi!
I've got to model electrical constraints on a net of a pcb. So, a net can be constrained either by layer,net class (and constraint name) or constraint class (and constraint name).
The problem I have is that a constraint (with a name and a bunch of attributes)
can be either
- a "free constraint, adressed by layer, net class and name or
I can enforce this easily with a table constraint (id set1 xor id set2 is true), but
can I put this into an ER diagram too?
Lots of Greetings!