Abstract
We propose to attribute one or more precisely defined levels of
semantic significance to every co-relationship in a relational
data base. We also propose a precise definition of a relationship,
and define a co-relationship as one of the two non trivial primitive
relationship types, that is, a co-relationship occurs between two
relations when a relationship relation can be formed with a single
join on join attributes of the two relations that are neither primary
nor candidate key attributes. It is shown that a co-relationship will
give rise to a connection trap when users assume either a level of
significance for the co-relationship that is too high, or which is
correct but not supported by the data in the data base. Furthermore,
anticipation by data base designers of user assumptions about levels of
significance for co-relationships, and consequent data base
modifications to avoid connection traps, will be very much a matter
of judgement of user behavioral probabilities, thus rendering both
automated data base design algorithms and universal relation generation
algorithms prone to failure.
Notes
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