
Skeleton entity-relationship models
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Although an entity-relationship type diagram describes many of the important features
of a conceptual model, it does not show the attributes associated with the entity and
relationship types. This additional information can be represented conveniently in the
form of a set of fully-normalised table types. In principle, one could define a table type
for each and every entity and relationship type, but the number of table types so
generated would often be unnecessarily large.
In practice, an entity type is almost always represented by its own table type, whereas
most relationship types are not. On E-R ...