A many:many relationship between two entity types can be decomposedinto two
1:many relationships. Knowing how to perform this trick is important for two reasons.
Firstly, as shown in Chapter 11, it will make it easy to spot certain unsatisfactory
features which may be present in an entity-relationship type diagram; secondly, some
database management systems are not capable of representing many:many
relationships directly, so all such relationships must be broken down into 1:many
relationships.
It is often assumed that the decomposition can be done as shown in Fig. 10.1, but
such an assumption ...
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