(b)Fig. 11.2a to connect Department and Employee directly;
(c)the type diagram in question 1 above, to connect Division and Department
directly.(5 min)
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Our final example is of a situation which cannot be resolved merely by adding an
additional relationship type. Suppose any supplier can supply any part to any customer.
An attempt at an entity-relationship diagram is shown in Fig. 11.4a. By decomposing
the many:many relationships into 1:many relationships (Fig. 11.4b) it can be seen that
the diagram conceals a many:1/1:many structure, and should therefore be regarded
with particular caution. A fairly obvious connection trap in ...
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