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Re: Primary and Foreign Keys
- From: Ronald Bourret <email@example.com>
- To: xml-dev <firstname.lastname@example.org>
- Date: Tue, 24 Jul 2001 23:03:55 -0700
"Thomas B. Passin" wrote:
> Another situation would arise if a table is a "join" table (Mike Gorman's
> term is more charming, though: "intertwinkle" table). That generally means
> a many-to-many relationship. The primary key for a join table is usually
> compound, which leaves ID/IDRef out unless you use two of them in each
I like intertwinkle.
Many-to-many relationships cause a special problem with nesting. When
using a canonical object-relational mapping, they result in an extra
element (representing the join row) between the elements corresponding
to the joined rows. This element usually needs to be removed by XSLT or
by smarts in the data transfer software.