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Posted by Erland Sommarskog on 06/01/05 11:42
(martind-crap1@mailblocks.com) writes:
> These are all very good thoughts, thanks. What happens if I have
> multiple n-to-1 relationships to the same child (e.g.
> Publisher-Address, Agency-Address -- but Addresses are never shared
> among entities) and I want to make them bidirectional?
Addresses are admittedly somewhat difficult to handle. On the one hand,
the address of a publisher and the address of an agency could be considered
to be different objects. On the other, you may want to have a common
handling of addresses, and not duplicate it for the same entity.
What we do is that have have a table "addresses", and it can be referred
to by several entities. In our case, it is perfectly possible that an
address is shared. For instance, an auditor may recieve copies of a client's
account statement, but the auditor may himself also be a client.
The main problem with our arrangement as I see is not that an address
could incorrectly be shared between two entities when it shouldn't, but
that the same address is entered twice, because it's difficult to find a
good method for users to find an existing address.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinfo/productdoc/2000/books.asp
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