
(a) By deriving a new table occurrence which shows which equipment each supplier
sells or services, show that the result of combining the two 1:many relationships,
Sells and Services, into a single SellsOrServices relationship yields a many:many
rather than a 1:many relationship.
(b) Suggest a change to the enterprise rules which, without altering the entity-
relationship type diagram, would make SellsOrServices a 1:many relationship.
(3 min)
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1. (a) Similar to Fig. 10.1a. (b), (c) Similar to Fig. 10.3.
2.
The entity name ‘Class’ illustrates nicely the ambiguity of language. For example:
(i) Is pottery Monday 7–8 p.m. a different class to ...