© Shamkant B. Navathe CC
Entity-Relationship Exercise
Exercise ER-1
Exercise ER-2
Exercise ER-3
Exercise ER-4
Exercise ER-5
Exercise ER-6
Exercise ER-7
The minimum number of Cs that can be associated with one A is 1. I
know this because the existence of the C to A relationship is mandatory. The maximum number of Cs that can be associated with one A is unlimited (or many). I know this because the cardinality of the C to A relationship is 1-M.
Exercise ER-8
Diagrams 1, 2, 3, and 4 are consistent with the facts. Diagram 2 is
1 1
consistent because, although Jennifer leads more than one project, the diagram is ambiguous as regards to cardinality — it merely points out that the existence is optional. Diagram 4 is also consistent with the facts because of its ambiguity regarding existence, this time in both directions.
2 2
3 3
4 4
Exercise ER-9
